Set Dangerfile validation rule for CHANGELOG as warning

Author: AliAbdelfattah

Dangerfile

@@ -8,5 +8,5 @@ if github.pr_body.length < 3 && git.lines_of_code > 10
 end
 
 if !git.modified_files.include?("CHANGELOG.md") && !declared_trivial
-  fail("Please include a CHANGELOG entry. \nYou can find it at [CHANGELOG.md](https://github.com/Instabug/Instabug-Flutter/blob/master/CHANGELOG.md).", sticky: false)
+  warn("Please include a CHANGELOG entry. \nYou can find it at [CHANGELOG.md](https://github.com/Instabug/Instabug-Flutter/blob/master/CHANGELOG.md).", sticky: false)
 end