Upgrade actions/cache from v4 to v6 (node 20 warning) (#190)

Author: felickz

.github/actions/install-codeql/action.yml

@@ -21,7 +21,7 @@ runs:
 
     - name: Cache CodeQL
       id: cache-codeql
-      uses: actions/cache@v4
+      uses: actions/cache@v6
       with:
         # A list of files, directories, and wildcard patterns to cache and restore
         path: ${{github.workspace}}/codeql_home