ci: avoid workflow running in fork (SchemaStore#4795)

Author: btea

.github/workflows/github-pages.yml

@@ -23,6 +23,7 @@ jobs:
   # Build job.
   build:
     runs-on: 'ubuntu-latest'
+    if: ${{ github.repository_owner == 'SchemaStore' }}
     steps:
       - uses: 'actions/checkout@v4'
       - uses: 'actions/setup-node@v4'
@@ -43,6 +44,7 @@ jobs:
       name: 'github-pages'
       url: '${{ steps.deployment.outputs.page_url }}'
     runs-on: 'ubuntu-latest'
+    if: ${{ github.repository_owner == 'SchemaStore' }}
     needs: 'build'
     steps:
       - id: 'deployment'