Update push step to use GITHUB_TOKEN for authentication (#240)

Author: rffontenelle

.github/workflows/python-docs-theme.yml

@@ -103,5 +103,8 @@ jobs:
 
       - name: Push changes
         if: ${{ contains(fromJSON('["schedule", "workflow_dispatch"]'), github.event_name) }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
+          git remote set-url origin "https://x-access-token:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}.git"
           git push