chore: Update README.md

Author: franciscojavierarceo

README.md

@@ -9,7 +9,7 @@
 
 [![PyPI - Downloads](https://img.shields.io/pypi/dm/feast)](https://pypi.org/project/feast/)
 [![GitHub contributors](https://img.shields.io/github/contributors/feast-dev/feast)](https://github.com/feast-dev/feast/graphs/contributors)
-[![unit-tests](https://github.com/feast-dev/feast/actions/workflows/unit_tests.yml/badge.svg?branch=master&event=push)](https://github.com/feast-dev/feast/actions/workflows/unit_tests.yml)
+[![unit-tests](https://github.com/feast-dev/feast/actions/workflows/unit_tests.yml/badge.svg?branch=master&event=pull_request)](https://github.com/feast-dev/feast/actions/workflows/unit_tests.yml)
 [![integration-tests-and-build](https://github.com/feast-dev/feast/actions/workflows/master_only.yml/badge.svg?branch=master&event=push)](https://github.com/feast-dev/feast/actions/workflows/master_only.yml)
 [![java-integration-tests](https://github.com/feast-dev/feast/actions/workflows/java_master_only.yml/badge.svg?branch=master&event=push)](https://github.com/feast-dev/feast/actions/workflows/java_master_only.yml)
 [![linter](https://github.com/feast-dev/feast/actions/workflows/linter.yml/badge.svg?branch=master&event=push)](https://github.com/feast-dev/feast/actions/workflows/linter.yml)