🤖 docs: Use codecov as test link.

These changes were automatically generated by a transform whose code can be found at:
  - https://github.com/make-github-pseudonymous-again/rejuvenate/blob/042c55f2254a9efdce5074d537141d6f85a98927/src/transforms/docs:use-codecov-as-test-link.js
Please contact the author of the transform if you believe there was an error.

doc/scripts/header.js

@@ -17,7 +17,7 @@ domReady(() => {
 	header.insertBefore(projectname, header.firstChild);
 
 	const testlink = document.querySelector('header > a[data-ice="testLink"]');
-	testlink.href = 'https://coveralls.io/github/iterable-iterator/cycle';
+	testlink.href = 'https://app.codecov.io/gh/iterable-iterator/cycle';
 	testlink.target = '_BLANK';
 
 	const searchBox = document.querySelector('.search-box');