feat: Upload Release Assets for Signing

This adds a signing step for our release assets in preparation for #1354. Although the CSR is
not ready yet, this will make it easy for us to reference the download url when it is ready.

.github/workflows/release.yml

@@ -34,6 +34,16 @@ jobs:
         with:
           name: repack-unsigned
           path: _build/repack/
+      - uses: signpath/github-action-submit-signing-request@v0.3
+        id: sign
+        with:
+          api-token: '${{ secrets.SIGNPATH_API_TOKEN }}'
+          organization-id: '0cd9fc3f-b78d-4214-b152-b2e93c952e14'
+          project-slug: 'CKAN'
+          signing-policy-slug: 'test-signing'
+          github-artifact-name: 'repack-unsigned'
+          artifact-configuration-slug: release
+          wait-for-completion: true
 
   build-dmg:
     runs-on: ubuntu-latest