[ci] Move check-docs and lint jobs off Travis

.github/workflows/static_analysis.yml

@@ -0,0 +1,52 @@
+# contains tests that can run without compiling LightGBM, like
+# linters and documentation checks.
+name: Static Analysis
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
+
+env:
+  CONDA_ENV: test-env
+  GITHUB_ACTIONS: 'true'
+  PYTHON_VERSION: 3.8
+
+jobs:
+  test:
+    name: ${{ matrix.task }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - task: lint
+          - task: check-docs
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2.3.4
+        with:
+          fetch-depth: 5
+          submodules: true
+      - name: Setup and run tests
+        shell: bash
+        run: |
+          export TASK="${{ matrix.task }}"
+          export OS_NAME="linux"
+          export BUILD_DIRECTORY="$GITHUB_WORKSPACE"
+          export LGB_VER=$(head -n 1 VERSION.txt)
+          export CONDA=${HOME}/miniconda
+          export PATH=${CONDA}/bin:$HOME/.local/bin:${PATH}
+          $GITHUB_WORKSPACE/.ci/setup.sh
+          $GITHUB_WORKSPACE/.ci/test.sh
+  all-successful:
+    # https://github.community/t/is-it-possible-to-require-all-github-actions-tasks-to-pass-without-enumerating-them/117957/4?u=graingert
+    runs-on: ubuntu-latest
+    needs: [test]
+    steps:
+    - name: Note that all tests succeeded
+      run: echo "🎉"

.travis.yml

@@ -20,8 +20,6 @@ env:
     - TASK=sdist
     - TASK=bdist
     - TASK=if-else
-    - TASK=lint
-    - TASK=check-docs
     - TASK=mpi METHOD=source
     - TASK=mpi METHOD=pip PYTHON_VERSION=3.7
     - TASK=mpi METHOD=wheel PYTHON_VERSION=3.7
@@ -37,10 +35,6 @@ matrix:
       env: TASK=gpu METHOD=pip PYTHON_VERSION=3.6
     - os: osx
       env: TASK=gpu METHOD=wheel PYTHON_VERSION=3.7
-    - os: osx
-      env: TASK=lint
-    - os: osx
-      env: TASK=check-docs
 
 before_install:
   - test -n $CC  && unset CC