Update lint file.

.github/workflows/lint.yaml

@@ -1,22 +1,11 @@
 name: lint
 
 on:
-  - push
-  - pull_request
+  push:
+    branches:
+      - main
+  pull_request:
 
 jobs:
-  lint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-
-      - name: Set up Python
-        uses: actions/setup-python@v2
-        with:
-          python-version: 3.7
-
-      - name: Install
-        run: pip install -r <(curl https://raw.githubusercontent.com/lsst/linting/main/requirements.txt)
-
-      - name: Run linter
-        run: flake8
+  call-workflow:
+    uses: lsst/rubin_workflows/.github/workflows/lint.yaml@main