fix: invalidate assets cache if configuration or images changed

Author: zlataovce

.github/actions/setup-node-pnpm/action.yml

@@ -17,4 +17,7 @@ runs:
       uses: actions/cache@v4
       with:
         path: node_modules/.astro/assets
-        key: sharp
+        # presume that the image optimization configuration changed if the lockfile or config file changed
+        key: sharp-${{ hashFiles('pnpm-lock.yaml', 'astro.config.ts', 'src/**/*.png', 'src/**/*.webp', 'src/**/*.gif') }}
+        restore-keys: |
+          sharp-