specify rust-cache workspaces directory (#1337)

Author: demoray

.github/workflows/build.yml

@@ -36,6 +36,8 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: services
       - run: eng/scripts/services_tests.sh
       - name: display free disk space
         run: df -h /