[codex] Pin GitHub Actions workflow references (#15828)

Pin floating external GitHub Actions workflow refs to immutable SHAs.

Why are we doing this? Please see the rationale doc:
https://docs.google.com/document/d/1qOURCNx2zszQ0uWx7Fj5ERu4jpiYjxLVWBWgKa2wTsA/edit?tab=t.0

Did this break you? Please roll back and let hintz@ know

.github/workflows/rust-release.yml

@@ -19,8 +19,8 @@ jobs:
   tag-check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
-      - uses: dtolnay/rust-toolchain@1.92
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - uses: dtolnay/rust-toolchain@c2b55edffaf41a251c410bb32bed22afefa800f1 # 1.92
       - name: Validate tag matches Cargo.toml version
         shell: bash
         run: |
@@ -79,7 +79,7 @@ jobs:
             target: aarch64-unknown-linux-gnu
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
       - name: Print runner specs (Linux)
         if: ${{ runner.os == 'Linux' }}
         shell: bash
@@ -125,7 +125,7 @@ jobs:
             sudo apt-get update -y
             sudo DEBIAN_FRONTEND=noninteractive apt-get install -y libubsan1
           fi
-      - uses: dtolnay/rust-toolchain@1.93.0
+      - uses: dtolnay/rust-toolchain@a0b273b48ed29de4470960879e8381ff45632f26 # 1.93.0
         with:
           targets: ${{ matrix.target }}
 
@@ -235,7 +235,7 @@ jobs:
           cargo build --target ${{ matrix.target }} --release --timings --bin codex --bin codex-responses-api-proxy
 
       - name: Upload Cargo timings
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7
         with:
           name: cargo-timings-rust-release-${{ matrix.target }}
           path: codex-rs/target/**/cargo-timings/cargo-timing.html
@@ -374,7 +374,7 @@ jobs:
             zstd -T0 -19 --rm "$dest/$base"
           done
 
-      - uses: actions/upload-artifact@v7
+      - uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7
         with:
           name: ${{ matrix.target }}
           # Upload the per-binary .zst files as well as the new .tar.gz
@@ -420,7 +420,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Generate release notes from tag commit message
         id: release_notes
@@ -442,7 +442,7 @@ jobs:
 
           echo "path=${notes_path}" >> "${GITHUB_OUTPUT}"
 
-      - uses: actions/download-artifact@v8
+      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
         with:
           path: dist
 
@@ -492,12 +492,12 @@ jobs:
           fi
 
       - name: Setup pnpm
-        uses: pnpm/action-setup@v5
+        uses: pnpm/action-setup@a8198c4bff370c8506180b035930dea56dbd5288 # v5
         with:
           run_install: false
 
       - name: Setup Node.js for npm packaging
-        uses: actions/setup-node@v6
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6
         with:
           node-version: 22
 
@@ -505,7 +505,7 @@ jobs:
         run: pnpm install --frozen-lockfile
 
       # stage_npm_packages.py requires DotSlash when staging releases.
-      - uses: facebook/install-dotslash@v2
+      - uses: facebook/install-dotslash@1e4e7b3e07eaca387acb98f1d4720e0bee8dbb6a # v2
       - name: Stage npm packages
         env:
           GH_TOKEN: ${{ github.token }}
@@ -523,7 +523,7 @@ jobs:
           cp scripts/install/install.ps1 dist/install.ps1
 
       - name: Create GitHub Release
-        uses: softprops/action-gh-release@v2
+        uses: softprops/action-gh-release@153bb8e04406b158c6c84fc1615b65b24149a1fe # v2
         with:
           name: ${{ steps.release_name.outputs.name }}
           tag_name: ${{ github.ref_name }}
@@ -533,21 +533,21 @@ jobs:
           # (e.g. -alpha, -beta). Otherwise publish a normal release.
           prerelease: ${{ contains(steps.release_name.outputs.name, '-') }}
 
-      - uses: facebook/dotslash-publish-release@v2
+      - uses: facebook/dotslash-publish-release@9c9ec027515c34db9282a09a25a9cab5880b2c52 # v2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           tag: ${{ github.ref_name }}
           config: .github/dotslash-config.json
 
-      - uses: facebook/dotslash-publish-release@v2
+      - uses: facebook/dotslash-publish-release@9c9ec027515c34db9282a09a25a9cab5880b2c52 # v2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           tag: ${{ github.ref_name }}
           config: .github/dotslash-zsh-config.json
 
-      - uses: facebook/dotslash-publish-release@v2
+      - uses: facebook/dotslash-publish-release@9c9ec027515c34db9282a09a25a9cab5880b2c52 # v2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
@@ -582,7 +582,7 @@ jobs:
 
     steps:
       - name: Setup Node.js
-        uses: actions/setup-node@v6
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6
         with:
           node-version: 22
           registry-url: "https://registry.npmjs.org"