Fix URL in integration test

https://github.com/github/codeql-action/runs/822529558?check_suite_focus=true#step:4:43

.github/workflows/integration-testing.yml

@@ -54,7 +54,7 @@ jobs:
     - uses: ./../action/init
       with:
         languages: cpp,csharp,java,javascript,python
-        config-file: github/codeql-action/.github/codeql/custom-queries.yml@main
+        config-file: github/codeql-action/tests/multi-language-repo/.github/codeql/custom-queries.yml@main
     - name: Build code
       shell: bash
       run: ./build.sh