add set options to make the script more robust

- especially, they throw error so that it is got caught in CI/CD
  pipelines

Changes to be committed:
      modified:   add_issue_to_project.sh

Author: ilkermeliksitki

.github/workflows/add-issue-to-project/add_issue_to_project.sh

@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -euo pipefail # exit on error, undefined variable, or error in pipeline
+
 OWNER="ilkermeliksitki"
 REPO="german-dict"
 PROJECT=5