build assets in e2e pipeline

We want to run the e2e tests with the latest assets without the need to
commit them to the repository. Otherwise we would not see test
failures from changes to the js code as early as possible.

.github/workflows/ci.yml

@@ -166,7 +166,7 @@ jobs:
             deps-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}
 
       - name: Install dependencies
-        run: mix deps.get --only e2e
+        run: mix deps.get --only e2e --only dev
 
       - name: Restore npm cache
         uses: actions/cache@v2
@@ -176,10 +176,14 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-node-
 
-      - name: npm install and test
-        run: |
-          npm install
-          npm run e2e:test
+      - name: npm install (assets)
+        run: cd assets && npm install && cd ..
+
+      - name: Build assets
+        run: mix assets.build
+
+      - name: Run e2e tests
+        run: e2e:test
 
       - uses: actions/upload-artifact@v3
         if: always()