fix: Simplify pip cache directory handling in CI workflow

.gitea/workflows/ci_backup.yml

@@ -11,7 +11,6 @@ jobs:
     runs-on: ubuntu-latest
     env:
       APT_CACHER_NG: http://192.168.88.14:3142
-      PIP_CACHE_DIR: /root/.cache/pip
     steps:
       - uses: actions/checkout@v4
 
@@ -20,17 +19,10 @@ jobs:
         with:
           python-version: "3.12"
 
-      - name: Get pip cache dir
-        id: pip-cache
-        run: |
-          echo \"path=$(pip cache dir)\" >> $GITEA_OUTPUT
-          echo \"Pip cache dir: $(pip cache dir)\"
-          echo \"PIP_CACHE_DIR=$(pip cache dir)\" >> $GITEA_ENV
-
       - name: Cache pip dependencies
         uses: actions/cache@v4
         with:
-          path: ${{ PIP_CACHE_DIR }}
+          path: /root/.cache/pip
           key: ${{ runner.os }}-pip-${{ hashFiles('requirements.txt', 'requirements-test.txt', 'pyproject.toml') }}
           restore-keys: |
             ${{ runner.os }}-pip-