Set path directly without env variable

The path could not be found.
Perhaps the syntax for referring to the env variable was wrong.

.github/workflows/rtc-tools.yml

@@ -15,13 +15,11 @@ jobs:
   style:
     runs-on: ubuntu-latest
     timeout-minutes: 30
-    env:
-      PRE_COMMIT_HOME: "${{ github.workspace }}/.cache/pre-commit"
     steps:
     - uses: actions/checkout@v4
     - uses: actions/cache@v4
       with:
-        path: "${PRE_COMMIT_HOME}"
+        path: "${{ github.workspace }}/.cache/pre-commit"
         key: default
     - run: pip install pre-commit
     - run: pre-commit run --all-files --show-diff-on-failure