add cache cleanup workflow and recompress

- .github/workflows/cmake.yml: recompress cache before sending.
    - this may or may not help since zstd is already used by the cache
      action.
- .github/workflows/cleanup-caches.yml: add from documentation to
  cleanup 100 caches on PR close.

Signed-off-by: Aiden Woodruff <[email protected]>

Author: bobpaw

.github/workflows/cleanup-caches.yml

@@ -0,0 +1,28 @@
+name: Cleanup caches on closed PRs
+# From https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows#matching-a-cache-key
+on:
+  pull_request:
+    types: [ closed ]
+jobs:
+  cleanup:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+		steps:
+      - name: Cleanup
+        run: |
+          echo "Fetching list of cache keys"
+          cacheKeysForPR=$(gh cache list --ref $BRANCH --limit 100 --json id --jq '.[].id')
+
+          ## Setting this to not fail the workflow while deleting cache keys.
+          set +e
+          echo "Deleting caches..."
+          for cacheKey in $cacheKeysForPR
+          do
+              gh cache delete $cacheKey
+          done
+          echo "Done"
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          BRANCH: refs/pull/${{ github.event.pull_request.number }}/merge

.github/workflows/cmake.yml

@@ -125,5 +125,8 @@ jobs:
         ctest --test-dir ${{github.workspace}}/example/mpi-nompi/build
         --output-on-failure
 
-    - name: CCache statistics
-      run: ccache -sv
+    - name: CCache statistics and recompression
+      run: |
+        ccache -sv
+        CCACHE_COMPRESSLEVEL=5 ccache -X
+