Prevent upload to swift if its from a fork (#60)

Reviewed-on: #60
Reviewed-by: Tino Schreiber <tino.schreiber@t-systems.com>
Co-authored-by: Sebastian Gode <sebastian.gode@telekom.de>
Co-committed-by: Sebastian Gode <sebastian.gode@telekom.de>

otc_metadata/templates/build-pdf-docs.yaml.j2

@@ -12,6 +12,9 @@ jobs:
           tox-env: pdf-docs
           
       - name: Upload documentation preview
+        {% raw -%}
+        if: ${{ github.event.pull_request.head.repo.full_name == github.repository }}
+        {%- endraw %}
         uses: https://github.com/opentelekomcloud-infra/github-actions/.github/actions/tox-upload-swift@v1
       {%- elif environment == 'public' %}
       - uses: opentelekomcloud-infra/github-actions/.github/actions/tox-run-env@v1
@@ -19,6 +22,9 @@ jobs:
           tox-env: pdf-docs
           
       - name: Upload documentation preview
+        {% raw -%}
+        if: ${{ github.event.pull_request.head.repo.full_name == github.repository }}
+        {%- endraw %}
         uses: opentelekomcloud-infra/github-actions/.github/actions/tox-upload-swift@v1
       {%- endif %}
         with: