fix: try to populate the Windows cache for release builds when PRs are put up for review (#2884)

Windows release builds take close to 12 minutes whereas Mac/Linux are
closer to 5. Let's see if this speeds things up?

.github/workflows/rust-ci.yml

@@ -103,12 +103,17 @@ jobs:
 
           # Also run representative release builds on Mac and Linux because
           # there could be release-only build errors we want to catch.
+          # Hopefully this also pre-populates the build cache to speed up
+          # releases.
           - runner: macos-14
             target: aarch64-apple-darwin
             profile: release
           - runner: ubuntu-24.04
             target: x86_64-unknown-linux-musl
             profile: release
+          - runner: windows-latest
+            target: x86_64-pc-windows-msvc
+            profile: release
 
     steps:
       - uses: actions/checkout@v5