CI: Don't use self-hosted runner on forks

.github/workflows/prepare-docs.yml

@@ -26,7 +26,7 @@ jobs:
     # docs builds are needed for anything on main, any tagged versions, and any tag
     # or branch starting with docs-preview
     needs: check_docs_rebuild
-    if: ${{ needs.check_docs_rebuild.outputs.should_skip != 'true' }}
+    if: ${{ needs.check_docs_rebuild.outputs.should_skip != 'true' && github.repository == 'YosysHQ/Yosys' }}
     runs-on: [self-hosted, linux, x64, fast]
     steps:
       - name: Checkout Yosys

.github/workflows/test-build.yml

@@ -253,7 +253,7 @@ jobs:
     name: Try build docs
     runs-on: [self-hosted, linux, x64, fast]
     needs: [pre_docs_job]
-    if: needs.pre_docs_job.outputs.should_skip != 'true'
+    if: ${{ needs.pre_docs_job.outputs.should_skip != 'true' && github.repository == 'YosysHQ/Yosys' }}
     strategy:
       matrix:
         docs-target: [html, latexpdf]

.github/workflows/test-verific.yml

@@ -27,7 +27,7 @@ jobs:
 
   test-verific:
     needs: pre-job
-    if: needs.pre-job.outputs.should_skip != 'true'
+    if: ${{ needs.pre-job.outputs.should_skip != 'true' && github.repository == 'YosysHQ/Yosys' }}
     runs-on: [self-hosted, linux, x64, fast]
     steps:
       - name: Checkout Yosys