Correctly save and restore cache in GH actions

Author: maksbotan

.github/workflows/master.yml

@@ -75,6 +75,15 @@ jobs:
         (cd servant-conduit && eval $DOCTEST)
         (cd servant-pipes && eval $DOCTEST)
 
+    - name: Save cache
+      uses: actions/cache/save@v3
+      if: always()
+      with:
+        path: |
+          ${{ steps.setup-haskell-cabal.outputs.cabal-store }}
+          dist-newstyle
+        key: ${{ runner.os }}-${{ matrix.ghc }}-${{ hashFiles('cabal.project.freeze') }}
+
   # stack:
   #   name: stack / ghc ${{ matrix.ghc }}
   #   runs-on: ubuntu-latest
@@ -130,7 +139,7 @@ jobs:
         cat cabal.project
         nix-shell ghcjs.nix --run "cabal v2-update && cabal v2-freeze"
 
-    - uses: actions/cache/save@v3
+    - uses: actions/cache/restore@v3
       name: Cache ~/.cabal/store and dist-newstyle
       with:
         path: |
@@ -147,3 +156,12 @@ jobs:
     - name: Tests
       run: |
         nix-shell ghcjs.nix --run ".github/run-ghcjs-tests.sh"
+
+    - name: Save cache
+      uses: actions/cache/save@v3
+      if: always()
+      with:
+        path: |
+          ~/.cabal/store
+          dist-newstyle
+        key: ${{ runner.os }}-ghcjs8.6-${{ hashFiles('cabal.project.freeze') }}