Create lint.yml action file.

This will replace Travis-CI.

.github/workflows/lint.yml

@@ -0,0 +1,34 @@
+name: Lint
+'on':
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+jobs:
+  Build:
+    runs-on: '${{ matrix.os }}'
+    strategy:
+      matrix:
+        os:
+          - ubuntu-18.04
+        python-version:
+          - '3.7'
+    steps:
+      - name: 'Set up Python ${{ matrix.python-version }}'
+        uses: actions/setup-python@v2
+        with:
+          python-version: '${{ matrix.python-version }}'
+      - uses: actions/checkout@v2
+      - run: >-
+          cd .. && git clone https://github.com/haikuports/haikuporter.git --depth=1 && cd haikuports
+      - run: 'PATH=$PATH:../haikuporter && export PATH'
+      - run: >-
+          printf 'TREE_PATH="'`pwd`'"\nPACKAGER="Nobody <server@fake>"\nTARGET_ARCHITECTURE="x86"\n' >haikuports.conf
+      - run: >-
+          wget https://github.com/waddlesplash/haiku-licenses/archive/master.zip
+          && unzip master.zip
+      - run: >-
+          ./lint-new-recipes.sh --config=haikuports.conf
+          --licenses=haiku-licenses-master