TEMP: pin action-prebuildify to fix/rust-binary-copy branch for CI validation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: szegedi

.github/workflows/build.yml

@@ -33,7 +33,7 @@ jobs:
           crate: '${{ matrix.crate }}'
 
   build:
-    uses: Datadog/action-prebuildify/.github/workflows/build.yml@main
+    uses: Datadog/action-prebuildify/.github/workflows/build.yml@fix/rust-binary-copy
     needs: build-test-wasm
     with:
       package-manager: 'yarn'