[CI] Move to newer latex action

.gitea/workflows/build-docs.yml

@@ -16,10 +16,8 @@ jobs:
           username: ${{ vars.REGISTRY_USER_USERNAME }}
           password: ${{ secrets.REGISTRY_USER_PASSWORD }}
           registry: ${{ vars.REGISTRY_BASE_URL }}
-      - name: Check auth
-        run: "cat ~/.docker/config.json | grep git.janishutz"
       - name: Run build
-        uses: actions/latex@v2
+        uses: actions/latex@main
         with:
           args: "-latexoption=-file-line-error -latexoption=-interaction=nonstopmode docs/docs.tex"
           image: ${{ vars.REGISTRY_NAME }}/latex-build