replace exit(main()) with raise SystemExit(main())

Committed via https://github.com/asottile/all-repos
diff --git a/pre_commit_hooks/detect_aws_credentials.py b/pre_commit_hooks/detect_aws_credentials.py
index 1663cfd..ba1d789 100644
--- a/pre_commit_hooks/detect_aws_credentials.py
+++ b/pre_commit_hooks/detect_aws_credentials.py
@@ -149,4 +149,4 @@
 
 
 if __name__ == '__main__':
-    exit(main())
+    raise SystemExit(main())