ci(gh-actions): Configure additional Cachix caches

Author: PetarKirov

.github/workflows/ci.yml

@@ -65,6 +65,7 @@ jobs:
         with:
           name: ${{ vars.CACHIX_CACHE }}
           authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
+          extraPullNames: ${{ vars.EXTRA_CACHIX_CACHES }}
 
       - name: Build ${{ matrix.package }}
         run: nix build -L --json --no-link '.#${{ matrix.attrPath }}'