chore: make pull builds only run for releasable branches

Author: kentcdodds

.github/workflows/validate.yml

@@ -1,5 +1,16 @@
 name: validate
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      [
+        '+([0-9])?(.{+([0-9]),x}).x',
+        'master',
+        'next',
+        'next-major',
+        'beta',
+        'alpha',
+      ]
+  pull_request: {}
 jobs:
   main:
     strategy: