CI badge: Only report status of vcmi/vcmi, ignore statuses of PRs

Show status of latest scheduled CI run on the develop branch.
Until now, the status of the latest CI run was shown, even if that was triggered by a PR

docs/Readme.md

@@ -1,4 +1,4 @@
-[![GitHub](https://github.com/vcmi/vcmi/actions/workflows/github.yml/badge.svg)](https://github.com/vcmi/vcmi/actions/workflows/github.yml)
+[![VCMI](https://github.com/vcmi/vcmi/actions/workflows/github.yml/badge.svg?event=schedule)](https://github.com/vcmi/vcmi/actions/workflows/github.yml)
 [![Github Downloads](https://img.shields.io/github/downloads/vcmi/vcmi/1.4.0/total)](https://github.com/vcmi/vcmi/releases/tag/1.4.0)
 [![Github Downloads](https://img.shields.io/github/downloads/vcmi/vcmi/1.4.1/total)](https://github.com/vcmi/vcmi/releases/tag/1.4.1)
 [![Github Downloads](https://img.shields.io/github/downloads/vcmi/vcmi/1.4.2/total)](https://github.com/vcmi/vcmi/releases/tag/1.4.2)