git-commit-checks: handle empty PR body

Handle the case where the PR body is empty.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

Author: jsquyres

.github/workflows/git-commit-checks.py

@@ -301,7 +301,7 @@ def check_github_pr_description(config):
     pr_num = int(match.group(1))
     pr     = repo.get_pull(pr_num)
 
-    if NACP in pr.body:
+    if pr.body and NACP in pr.body:
         config['cherry pick required'] = False
 
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