Use codecov.yml to stop comments (#397)

We get enough information from the CI status.

MANIFEST.in

@@ -1,7 +1,7 @@
 include LICENSE *.rst *.toml .readthedocs.yml .pre-commit-config.yaml
 
 # Don't package GitHub-specific files.
-exclude .github/*.md .travis.yml
+exclude .github/*.md .travis.yml codecov.yml
 
 # Tests
 include tox.ini .coveragerc conftest.py

codecov.yml

@@ -0,0 +1,10 @@
+---
+comment: false
+coverage:
+    status:
+        patch:
+            default:
+                target: "100"
+        project:
+            default:
+                target: "100"