Fix CI for Firebase repo now using main (#143)

README.md

@@ -161,7 +161,7 @@ Alternatively disable signing in each target:
 ### Code Formatting
 
 To ensure that the code is formatted consistently, run the script
-[./scripts/check.sh](https://github.com/firebase/firebase-ios-sdk/blob/master/scripts/check.sh)
+[./scripts/check.sh](https://github.com/firebase/firebase-ios-sdk/blob/main/scripts/check.sh)
 before creating a PR.
 
 GitHub Actions will verify that any code changes are done in a style compliant

setup-scripts.sh

@@ -17,6 +17,6 @@ git clone \
   https://github.com/firebase/firebase-ios-sdk.git \
 ;
 cd firebase-ios-sdk
-git checkout master -- scripts
+git checkout main -- scripts
 cd ..
 ln -s firebase-ios-sdk/scripts scripts