Merge pull request #787 from IntersectMBO/mgalazyn/chore/use-ghc-patch-version-in-cache-name

GHA | add GHC patch version to the cache name

Author: Jimbo4350

.github/workflows/haskell.yml

@@ -98,7 +98,11 @@ jobs:
 
     # Use a fresh cache each month
     - name: Store month number as environment variable used in cache version
-      run:  echo "MONTHNUM=$(date -u '+%m')" >> $GITHUB_ENV
+      run: |
+        cat <<EOF >> $GITHUB_ENV
+        MONTHNUM=$(date -u '+%m')
+        GHC=$(ghc --numeric-version)
+        EOF
 
     # From the dependency list we restore the cached dependencies.
     # We use the hash of `dependencies.txt` as part of the cache key because that will be stable
@@ -111,10 +115,10 @@ jobs:
           ${{ steps.setup-haskell.outputs.cabal-store }}
           dist-newstyle
         key:
-          cache-${{ env.CABAL_CACHE_VERSION }}-${{ runner.os }}-${{ matrix.ghc }}-${{ env.MONTHNUM }}-${{ hashFiles('dependencies.txt') }}
+          cache-${{ env.CABAL_CACHE_VERSION }}-${{ runner.os }}-${{ env.GHC }}-${{ env.MONTHNUM }}-${{ hashFiles('dependencies.txt') }}
         # try to restore previous cache from this month if there's no cache for the dependencies set
         restore-keys: |
-          cache-${{ env.CABAL_CACHE_VERSION }}-${{ runner.os }}-${{ matrix.ghc }}-${{ env.MONTHNUM }}-
+          cache-${{ env.CABAL_CACHE_VERSION }}-${{ runner.os }}-${{ env.GHC }}-${{ env.MONTHNUM }}-
 
     # Now we install the dependencies. If the cache was found and restored in the previous step,
     # this should be a no-op, but if the cache key was not found we need to build stuff so we can