add a license checker CI

Signed-off-by: 天元 <jianbo.sjb@alibaba-inc.com>

.github/workflows/license.yml

@@ -0,0 +1,26 @@
+name: license
+on:
+  push:
+    branches:
+      - master
+      - release-*
+  workflow_dispatch: {}
+  pull_request:
+    branches:
+      - master
+      - release-*
+
+jobs:
+  license_check:
+    runs-on: ubuntu-latest
+    name: Check for unapproved licenses
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.6
+      - name: Install dependencies
+        run: gem install license_finder
+      - name: Run tests
+        run: license_finder --decisions_file .license/dependency_decisions.yml

.license/README.md

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+# License Checker
+
+Our license checker CI rely on [LicenseFinder](https://github.com/pivotal/LicenseFinder).
+
+## How to add a new license
+
+LicenseFinder is a ruby project, so make sure you have ruby installed.
+
+### Install the tool
+
+```shell
+gem install license_finder
+```
+
+### Add a license
+
+```shell
+license_finder  permitted_licenses add MIT --decisions_file .license/dependency_decisions.yml
+```

.license/dependency_decisions.yml

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+---
+- - :permit
+  - MIT
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:35:34.645031000 Z
+- - :permit
+  - Apache 2.0
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:19:18.243194000 Z
+- - :permit
+  - New BSD
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:19:28.540675000 Z
+- - :permit
+  - Simplified BSD
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:20:01.774212000 Z
+- - :permit
+  - Mozilla Public License 2.0
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:21:05.194536000 Z
+- - :permit
+  - unknown
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:21:43.379269000 Z
+- - :permit
+  - ISC
+  - :who: 
+    :why: 
+    :versions: []
+    :when: 2021-03-12 07:22:07.265966000 Z