chore: fix branch name on update-version workflow (GoogleCloudPlatform#490)

shubha-rajan · web-flow · commit 8aeeae395f8b · 2020-09-29T20:48:04.000Z
## Change Description

The action isn't triggering and I suspect it's because of these missing quotes.
diff --git a/.github/workflows/update-versions.yml b/.github/workflows/update-versions.yml
@@ -2,7 +2,7 @@
 name: update-version
 on:
   pull_request:
-          branches: [master]
+          branches: ['master']
           paths: 
             - 'version.txt'
 
