set github-actions git credentials

Author: kernc

.github/deploy-gh-pages.sh

@@ -20,6 +20,12 @@ sitemap() {
     echo "Sitemap: $WEBSITE/sitemap.txt" > 'robots.txt'
 }
 
+if ! git config user.name; then
+    echo 'setting'
+    git config user.name 'github-actions'
+    git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
+fi
+
 head=$(git rev-parse HEAD)
 
 git clone -b gh-pages "https://kernc:$GH_PASSWORD@github.com/$GITHUB_REPOSITORY.git" gh-pages