Fix CI badge in README (#26)

Author: frenck

README.md

@@ -10,7 +10,7 @@
 ![Supports amd64 Architecture][amd64-shield]
 ![Supports i386 Architecture][i386-shield]
 
-[![GitLab CI][gitlabci-shield]][gitlabci]
+[![Github Actions][github-actions-shield]][github-actions]
 ![Project Maintenance][maintenance-shield]
 [![GitHub Activity][commits-shield]][commits]