Update CI config (#48)

Author: wojtekmach

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  test:
+    runs-on: ubuntu-16.04
+    env:
+      MIX_ENV: test
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - pair:
+              elixir: 1.3.4
+              otp: 19.3.6.13
+          - pair:
+              elixir: 1.11.3
+              otp: 23.2.5
+            lint: lint
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: erlef/setup-elixir@v1
+        with:
+          otp-version: ${{matrix.pair.otp}}
+          elixir-version: ${{matrix.pair.elixir}}
+
+      - name: Install Dependencies
+        run: mix deps.get --only test
+
+      - run: mix format --check-formatted
+        if: ${{ matrix.lint }}
+
+      - run: mix deps.get && mix deps.unlock --check-unused
+        if: ${{ matrix.lint }}
+
+      - run: mix deps.compile
+
+      - run: mix compile --warnings-as-errors
+        if: ${{ matrix.lint }}
+
+      - run: mix test

.travis.yml

@@ -1,6 +1,6 @@
 # A Make compiler for Mix
 
-[![Build Status](https://travis-ci.org/elixir-lang/elixir_make.svg?branch=master)](https://travis-ci.org/elixir-lang/elixir_make)
+[![Build Status](https://github.com/elixir-lang/elixir_make/workflows/CI/badge.svg)](https://github.com/elixir-lang/elixir_make/actions)
 
 This project provides a Mix compiler that makes it straight-forward to use makefiles in your Mix projects.