feat(ci): add style task

ci/pipelines/pull-requests.yaml

@@ -25,6 +25,37 @@ resources:
       disable_forks: false
 
 jobs:
+  - name: style
+    max_in_flight: 4
+    plan:
+      - get: quay-pull-request
+        trigger: true
+        version: every
+
+      - get: build-image
+
+      - put: quay-pull-request
+        params:
+          path: quay-pull-request
+          context: style
+          status: pending
+
+      - task: style
+        image: build-image
+        file: quay-pull-request/ci/tasks/style.yaml
+        on_success:
+          put: quay-pull-request
+          params:
+            path: quay-pull-request
+            context: style
+            status: success
+        on_failure:
+          put: quay-pull-request
+          params:
+            path: quay-pull-request
+            context: style
+            status: failure
+
   - name: karma
     max_in_flight: 4
     plan:

ci/tasks/style.yaml

@@ -0,0 +1,13 @@
+---
+platform: linux
+inputs:
+  - name: quay-pull-request
+run:
+  path: /bin/sh
+  args:
+    - -c
+    - |
+      set -eux
+      pip install --quiet -r quay-pull-request/requirements-dev.txt
+      cd quay-pull-request
+      yapf -d -r .