CI: don't run Actions on forks, allow skipping ci

Author: rgommers

.github/workflows/pages.yml

@@ -7,6 +7,8 @@ on:
     - "**"
 jobs:
   run:
+    # Don't run Action on forks, and allow skipping CI
+    if: "github.repository == 'data-apis/array-api' && !contains(github.event.head_commit.message, '[ci skip]') && !contains(github.event.head_commit.message, '[skip ci]') && !contains(github.event.head_commit.message, '[skip github]')"
     runs-on: ubuntu-18.04
     steps:
     # - uses: docker://pandoc/latex:2.9