Prevent < and > in commit titles from breaking dag-sync slack message (…

…#2837)

* Prevent < and > in commit titles from breaking dag-sync slack message

* Use HTML entities rather than odd unicode characters

dag-sync.sh

@@ -30,6 +30,10 @@ have_dag=$(git log -p -1 "$new" --pretty=format: --name-only | grep "catalog/dag
 
 # Pull out the subject from the new commit
 subject=$(git log -1 --format='%s')
+# Swap the < & > characters for their HTML entities so they aren't
+# interpreted as delimiters by Slack
+subject=${subject//>/&gt;}
+subject=${subject//</&lt;}
 
 if [ -z "$SLACK_URL" ]; then
   echo "Slack hook was not supplied! Updates will not be posted"