fix(ci) lock rust toolchain at 1.93.0 to unblock (#11703)

## Summary
CI is broken on main because our CI toolchain is trying to run 1.93.1
while our rust toolchain is locked at 1.93.0. I'm sure it's likely safe
to upgrade, but let's keep things stable for now.

## Testing
- [x] CI should hopefully pass

.github/workflows/rust-release.yml

@@ -123,7 +123,7 @@ jobs:
             sudo apt-get update -y
             sudo DEBIAN_FRONTEND=noninteractive apt-get install -y libubsan1
           fi
-      - uses: dtolnay/rust-toolchain@1.93
+      - uses: dtolnay/rust-toolchain@1.93.0
         with:
           targets: ${{ matrix.target }}