chore: switch Codecov PR comment to default behavior (#1415)

It's super annoying to get dozens of meaningless codecov notifications in my inbox every day, because of the current behavior. Switching to default to "update, if exists. Otherwise post new"

Ref: https://docs.codecov.com/docs/pull-request-comments#behavior

Author: thymikee

.codecov.yml

@@ -4,6 +4,6 @@ coverage:
   range: 70...100
 
 comment:
-  behavior: new
+  behavior: default
   require_changes: false
   require_base: no