fix: remove cache: pip from setup-python

Because there is no requirements.txt, the pip cache step fails. Removed cache since installing mkdocs-material is very fast.

Author: VoChiDanh

.github/workflows/wiki.yml

@@ -25,7 +25,6 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: 3.x
-          cache: 'pip'
 
       - name: Install dependencies
         run: |