Add golangci-lint

Signed-off-by: Howard Lau <howardlau1999@hotmail.com>

.github/workflows/lint.yml

@@ -0,0 +1,29 @@
+name: Lint
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+jobs:
+  golangci:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v2
+        with:
+          # Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.
+          version: v1.31
+
+          # Optional: working directory, useful for monorepos
+          # working-directory: somedir
+
+          # Optional: golangci-lint command line arguments.
+          # TODO: remove disabled
+          args: -D errcheck -D deadcode -D unused
+
+          # Optional: show only new issues if it's a pull request. The default value is `false`.
+          # only-new-issues: true