Update code coverage badge and link

Author: garydgregory

README.md

@@ -44,7 +44,7 @@ Apache Commons CLI
 ===================
 
 [![GitHub Actions Status](https://github.com/apache/commons-cli/workflows/Java%20CI/badge.svg)](https://github.com/apache/commons-cli/actions)
-[![Coverage Status](https://coveralls.io/repos/apache/commons-cli/badge.svg)](https://coveralls.io/r/apache/commons-cli)
+[![Coverage Status](https://codecov.io/gh/apache/commons-cli/branch/master/graph/badge.svg)](https://app.codecov.io/gh/apache/commons-cli/branch/master)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/commons-cli/commons-cli/badge.svg?gav=true)](https://maven-badges.herokuapp.com/maven-central/commons-cli/commons-cli/)
 [![Javadocs](https://javadoc.io/badge/commons-cli/commons-cli/1.5.0.svg)](https://javadoc.io/doc/commons-cli/commons-cli/1.5.0)
 [![CodeQL](https://github.com/apache/commons-cli/workflows/CodeQL/badge.svg)](https://github.com/apache/commons-cli/actions/workflows/codeql-analysis.yml?query=workflow%3ACodeQL)