ci: rename calens GitHub App secrets to APP_ID/APP_PRIVATE_KEY

Author: DeepDiver1975

.github/workflows/calens.yml

@@ -12,5 +12,5 @@ jobs:
   changelog:
     uses: owncloud/reusable-workflows/.github/workflows/calens.yml@main
     secrets:
-      CALENS_APP_ID: ${{ secrets.CALENS_APP_ID }}
-      CALENS_APP_PRIVATE_KEY: ${{ secrets.CALENS_APP_PRIVATE_KEY }}
+      APP_ID: ${{ secrets.CALENS_APP_ID }}
+      APP_PRIVATE_KEY: ${{ secrets.CALENS_APP_PRIVATE_KEY }}