fix: Refuse to run on pull_request event

Avoid merging pull requests, which is unlikely to be the intended
purpose of using this action.

Author: Kurt-von-Laven

entrypoint.sh

@@ -7,6 +7,12 @@ if [[ -z $INPUT_GITHUB_TOKEN ]]; then
   exit 1
 fi
 
+if [[ $GITHUB_EVENT_NAME == 'pull_request' ]]; then
+  echo "Refusing to run on pull_request event since this would merge the pull request." >&2
+  echo "You probably want to run on push to your default branch instead." >&2
+  exit 1
+fi
+
 echo "Configuring Git username, email, and pull behavior..."
 git config --local user.name "${INPUT_GIT_NAME}"
 git config --local user.email "${INPUT_GIT_EMAIL}"