Remove references to master branch. (GoogleCloudPlatform#97)

Author: jsuereth

.github/workflows/pr-build.yml

@@ -3,10 +3,7 @@ name: "Pull Request Build"
 on:
   pull_request:
     branches:
-      - master
       - main
-      # For Testing!
-      - wip-test-containers
 jobs:
   test:
     name: Test
@@ -39,4 +36,4 @@ jobs:
       - uses: burrunan/[email protected]
         with:
           remote-build-cache-proxy-enabled: false
-          arguments: spotlessCheck
+          arguments: spotlessCheck

RELEASING.md

@@ -82,7 +82,7 @@ $ ./gradlew snapshot -Dmock.server.path=$MOCKSERVER
 
 ## Releasing a Candidate
 
-After following the above steps, you can release candidates from `master` or `v<major>.<minor>.x` branches.
+After following the above steps, you can release candidates from `main` or `v<major>.<minor>.x` branches.
 
 For example, to release the v0.14.0-RC1 candidate, do the following:
 
@@ -101,7 +101,7 @@ Note:  In the future, the `-Prelease.version` flag should not be required.
 
 ## Release a final verison
 
-After following the above steps, you can release candidates from `master` or `v<major>.<minor>.x` branches.
+After following the above steps, you can release candidates from `main` or `v<major>.<minor>.x` branches.
 
 For example, to release the v0.14.0 candidate, do the following: