Complete the transition from Travis to GitHub Actions (#8592)

Author: paulb777

.travis.yml

@@ -27,7 +27,6 @@
 [![Actions Status][gh-storage-badge]][gh-actions]
 [![Actions Status][gh-symbolcollision-badge]][gh-actions]
 [![Actions Status][gh-zip-badge]][gh-actions]
-[![Travis](https://travis-ci.org/firebase/firebase-ios-sdk.svg?branch=master)](https://travis-ci.org/firebase/firebase-ios-sdk)
 
 # Firebase Apple Open Source Development