add lint workflow

.github/workflows/lint.yml

@@ -0,0 +1,55 @@
+name: Lint
+
+on:
+  pull_request:
+
+jobs:
+  quick-checks:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fetch CosyVoice
+        uses: actions/checkout@v1
+      - name: Checkout PR tip
+        run: |
+          set -eux
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            # We are on a PR, so actions/checkout leaves us on a merge commit.
+            # Check out the actual tip of the branch.
+            git checkout ${{ github.event.pull_request.head.sha }}
+          fi
+          echo ::set-output name=commit_sha::$(git rev-parse HEAD)
+        id: get_pr_tip
+      - name: Ensure no tabs
+        run: |
+          (! git grep -I -l $'\t' -- . ':(exclude)*.txt' ':(exclude)*.svg' ':(exclude)**Makefile' ':(exclude)**/contrib/**' ':(exclude)third_party' ':(exclude).gitattributes' ':(exclude).gitmodules' || (echo "The above files have tabs; please convert them to spaces"; false))
+      - name: Ensure no trailing whitespace
+        run: |
+          (! git grep -I -n $' $' -- . ':(exclude)*.txt' ':(exclude)third_party' ':(exclude).gitattributes' ':(exclude).gitmodules' || (echo "The above files have trailing whitespace; please remove them"; false))
+
+  flake8-py3:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Setup Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.9
+          architecture: x64
+      - name: Fetch CosyVoice
+        uses: actions/checkout@v1
+      - name: Checkout PR tip
+        run: |
+          set -eux
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            # We are on a PR, so actions/checkout leaves us on a merge commit.
+            # Check out the actual tip of the branch.
+            git checkout ${{ github.event.pull_request.head.sha }}
+          fi
+          echo ::set-output name=commit_sha::$(git rev-parse HEAD)
+        id: get_pr_tip
+      - name: Run flake8
+        run: |
+          set -eux
+          pip install flake8==3.8.2 flake8-bugbear flake8-comprehensions flake8-executable flake8-pyi==20.5.0 mccabe pycodestyle==2.6.0 pyflakes==2.2.0
+          flake8 --version
+          flake8 --max-line-length 120 --exclude ./third_party/,./runtime/python/grpc/cosyvoice_pb2*py
+          if [ $? != 0 ]; then exit 1; fi