chore: add polkadotjs tests to ci

.github/workflows/tests.yml

@@ -156,3 +156,27 @@ jobs:
         name: Run stress
         run: |
           docker run chainsafe/gossamer:test sh -c "make it-grandpa"
+
+  docker-polkadotjs-tests:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      -
+        name: Build
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          load: true
+          file: ./Dockerfile
+          platforms: linux/amd64
+          push: false
+          tags: chainsafe/gossamer:test
+      -
+        name: Run polkadotjs tests
+        run: |
+          docker run chainsafe/gossamer:test sh -c "make it-polkadotjs"