Run asset building serverside

.github/workflows/django.yml

@@ -7,16 +7,27 @@ on:
     branches: [master]
 
 jobs:
-  build:
+  dependencies:
+    runs-on: ubuntu-latest
+    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+    steps:
+        - uses: actions/checkout@v2
+        - uses: bahmutov/npm-install@v1
+        - run: node node_modules/gulp/bin/gulp build
+        - name: Cache gulp output
+            uses: actions/cache@v2
+            with:
+                path: static/
+                key: static-${{ hashFiles('package-lock.json') }}-${{ hashFiles('RIGS/static') }}
+  test:
+    needs: dependencies
     env:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     runs-on: ubuntu-latest
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
     strategy:
       matrix:
         test-group: ["RIGS", "versioning", "users", "assets"]
     steps:
-      - uses: actions/checkout@v2
       - name: Set up Python
         uses: actions/setup-python@v2
         with: