fix: Update 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: ${{ github.workspace }}/.pip_cache
     steps:
       - uses: actions/checkout@v4
 
@@ -25,12 +24,12 @@ jobs:
         run: |
           echo \"path=$(pip cache dir)\" >> $GITEA_OUTPUT
           echo \"Pip cache dir: $(pip cache dir)\"
-          echo "PIP_CACHE_DIR=${{ env.PIP_CACHE_DIR }}" >> $GITEA_ENV
+          echo \"PIP_CACHE_DIR=$(pip cache dir)\" >> $GITEA_ENV
 
       - name: Cache pip dependencies
         uses: actions/cache@v4
         with:
-          path: ${{ PIP_CACHE_DIR }}
+          path: ${{ steps.pip-cache.outputs.path }}
           key: ${{ runner.os }}-pip-${{ hashFiles('requirements.txt', 'requirements-test.txt', 'pyproject.toml') }}
           restore-keys: |
             ${{ runner.os }}-pip-