refactor: using .nvmrc entry

https://github.com/actions/setup-node/blob/main/docs/advanced-usage.md#node-version-file

Author: mfranzke

.github/actions/npm-cache/action.yml

@@ -8,7 +8,7 @@ runs:
       # https://github.com/actions/setup-node
       uses: actions/setup-node@v4
       with:
-        node-version: 22
+        node-version-file: '.nvmrc'
 
     - name: Display node and npm version
       shell: bash