Fix Windows provider auth test helpers

codex-rs/core/src/models_manager/manager_tests.rs

@@ -145,7 +145,7 @@ mv tokens.next tokens.txt
             let script_path = tempdir.path().join("print-token.ps1");
             std::fs::write(
                 &script_path,
-                r#"$lines = Get-Content -Path tokens.txt
+                r#"$lines = @(Get-Content -Path tokens.txt)
 if ($lines.Count -eq 0) { exit 1 }
 Write-Output $lines[0]
 $lines | Select-Object -Skip 1 | Set-Content -Path tokens.txt

codex-rs/core/tests/suite/client.rs

@@ -190,7 +190,7 @@ mv tokens.next tokens.txt
             let script_path = tempdir.path().join("print-token.ps1");
             std::fs::write(
                 &script_path,
-                r#"$lines = Get-Content -Path tokens.txt
+                r#"$lines = @(Get-Content -Path tokens.txt)
 if ($lines.Count -eq 0) { exit 1 }
 Write-Output $lines[0]
 $lines | Select-Object -Skip 1 | Set-Content -Path tokens.txt

codex-rs/login/src/auth/auth_tests.rs

@@ -364,7 +364,7 @@ mv tokens.next tokens.txt
             let script_path = tempdir.path().join("print-token.ps1");
             std::fs::write(
                 &script_path,
-                r#"$lines = Get-Content -Path tokens.txt
+                r#"$lines = @(Get-Content -Path tokens.txt)
 if ($lines.Count -eq 0) { exit 1 }
 Write-Output $lines[0]
 $lines | Select-Object -Skip 1 | Set-Content -Path tokens.txt