chore: update validate.yml (#822)

Author: MichaelDeBoey

.github/workflows/validate.yml

@@ -2,19 +2,18 @@ name: validate
 on:
   push:
     branches:
-      [
-        '+([0-9])?(.{+([0-9]),x}).x',
-        'master',
-        'next',
-        'next-major',
-        'beta',
-        'alpha',
-        '!all-contributors/**',
-      ]
-  pull_request:
-    branches-ignore: ['all-contributors/**']
+      - '+([0-9])?(.{+([0-9]),x}).x'
+      - 'master'
+      - 'next'
+      - 'next-major'
+      - 'beta'
+      - 'alpha'
+      - '!all-contributors/**'
+  pull_request: {}
 jobs:
   main:
+    # ignore all-contributors PRs
+    if: ${{ !contains(github.head_ref, 'all-contributors') }}
     strategy:
       matrix:
         node: [10.14.2, 12, 14, 15]