chore(ci): add informational Codecov status checks

Hi, Tom from Codecov here. I noticed that you were using Codecov but weren't actually getting any notifications on pull requests. I figured it would be useful to get some idea if code being changed is being tested, but also not blocking CI/merging. Let me know if this makes sense or if we can do something that would be helpful.

.codecov.yml

@@ -1,5 +1,9 @@
 comment: false
 coverage:
     status:
-        project: off
+        project:
-        patch: off
+            default:
+                informational: true
+        patch:
+            default:
+                informational: true