iox-#2011 Fix warning in cache action

.github/workflows/lint_pull_request.yml

@@ -43,14 +43,15 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
+      - name: Calculate lychee cache key
+        id: lychee-cache-key
+        run: echo "::set-output name=key::$(date +'%G-%V')" # %G = year; %V = week number
+
       - name: Restore lychee cache
         uses: actions/cache@v3
-        if: always()
         with:
           path: .lycheecache
-          key: cache-lychee-all-branches
-          # the cache will not be updated and therefore needs to be recreated after 7 days
-          retention-days: 7
+          key: cache-lychee-all-branches-${{ steps.lychee-cache-key.outputs.key }}
 
       - name: Link Checker
         uses: lycheeverse/lychee-action@v1.8.0