Replace Travis CI with GitHub Actions

Travis just isn't what it used to be.

.github/workflows/tests.yml

@@ -0,0 +1,32 @@
+name: Run Tests
+
+on:
+  push:
+    branches:
+      - "master"
+      - "v3"
+
+jobs:
+  spec:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        ruby_version:
+          - "2.6"
+          - "2.7"
+          - "3.0"
+          - "3.1"
+          - "head"
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby_version }}
+        bundler-cache: true
+
+    - name: Run Tests
+      run: bundle exec rake

README.md

@@ -1,7 +1,7 @@
 # Interactor
 
 [![Gem Version](https://img.shields.io/gem/v/interactor.svg)](http://rubygems.org/gems/interactor)
-[![Build Status](https://img.shields.io/travis/collectiveidea/interactor/master.svg)](https://travis-ci.org/collectiveidea/interactor)
+[![Build Status](https://github.com/collectiveidea/interactor/actions/workflows/tests.yml/badge.svg)](https://github.com/collectiveidea/interactor/actions/workflows/tests.yml)
 [![Maintainability](https://img.shields.io/codeclimate/maintainability/collectiveidea/interactor.svg)](https://codeclimate.com/github/collectiveidea/interactor)
 [![Test Coverage](https://img.shields.io/codeclimate/coverage-letter/collectiveidea/interactor.svg)](https://codeclimate.com/github/collectiveidea/interactor)
 [![Ruby Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg)](https://github.com/testdouble/standard)