ci: tell git the workspace is safe

Otherwise the deployment fails with

```
ERROR   -  Failed to deploy to GitHub with error:
detected dubious ownership in repository at '/__w/docs/docs'
To add an exception for this directory, call:

	git config --global --add safe.directory /__w/docs/docs
```

Signed-off-by: Davide Cavalca <davide@cavalca.name>

Author: davide125

.github/workflows/pages.yml

@@ -23,6 +23,8 @@ jobs:
         run: |
           git config --global user.name github-actions[bot]
           git config --global user.email 41898282+github-actions[bot]@users.noreply.github.com
+          # This is needed for the deployment to work
+          git config --global --add safe.directory "$GITHUB_WORKSPACE"
       - name: Build
         if: github.event_name == 'pull_request'
         run: mkdocs build