[CI] Save cache on failures

Author: giordano

.github/workflows/ci.yml

@@ -22,6 +22,11 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+# needed to allow julia-actions/cache to delete old caches that it has created
+permissions:
+  actions: write
+  contents: read
+
 jobs:
   test:
     timeout-minutes: 60
@@ -58,6 +63,7 @@ jobs:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
       - uses: julia-actions/cache@v2
+        id: julia-cache
         with:
           cache-name: "tests"
       - uses: julia-actions/julia-buildpkg@v1
@@ -68,3 +74,11 @@ jobs:
           files: lcov.info
           token: ${{ secrets.CODECOV_TOKEN }}
         continue-on-error: true
+      - name: Save Julia depot cache on cancel or failure
+        id: julia-cache-save
+        if: cancelled() || failure()
+        uses: actions/cache/save@v4
+        with:
+          path: |
+            ${{ steps.julia-cache.outputs.cache-paths }}
+          key: ${{ steps.julia-cache.outputs.cache-key }}