Migrate from Travis CI to GitHub Actions (#59)

* Migrate from Travis CI to GitHub Actions
* Move dev dependencies to Gemfile and fix rake incompat with Ruby 3.2+
* Override rubygems only for Ruby 1.9

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: test on CI
+on:
+  push:
+    branches: [master]
+  pull_request:
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby:
+          [
+            "1.9",
+            "2.0",
+            "2.1",
+            "2.2",
+            "2.3",
+            "2.4",
+            "2.5",
+            "2.6",
+            "2.7",
+            "3.0",
+            "3.1",
+            "3.2",
+            "head",
+            "jruby-head",
+          ]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          rubygems: ${{ matrix.ruby == '1.9' && '2.7.11' || 'default' }}
+          bundler-cache: true
+      - name: Run tests
+        run: bundle exec rake test

Gemfile

@@ -1,4 +1,10 @@
 source "https://rubygems.org"
-
-# Specify your gem's dependencies in plist.gemspec
 gemspec
+
+if Gem::Requirement.new("< 2.2").satisfied_by?(Gem::Version.new(RUBY_VERSION))
+  gem "rake", "~> 11.3"
+else
+  gem "rake", "~> 13.0"
+end
+
+gem "test-unit", "~> 3.5"

README.rdoc

@@ -1,7 +1,7 @@
 = All-purpose Property List manipulation library
 
 {<img src="https://badge.fury.io/rb/plist.svg" alt="Gem Version" />}[https://rubygems.org/gems/plist]
-{<img src="https://travis-ci.org/patsplat/plist.svg?branch=master" alt="Build Status" />}[https://travis-ci.org/patsplat/plist]
+{<img src="https://github.com/patsplat/plist/actions/workflows/ci.yml/badge.svg" alt="Build Status" />}[https://github.com/patsplat/plist/actions/workflows/ci.yml]
 
 Plist is a library to manipulate Property List files, also known as plists.  It can parse plist files into native Ruby data structures as well as generating new plist files from your Ruby objects.
 

plist.gemspec

@@ -21,8 +21,4 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.required_ruby_version = ">= 1.9.3"
-
-  spec.add_development_dependency "bundler", ">= 1.14"
-  spec.add_development_dependency "rake", "~> 10.5"
-  spec.add_development_dependency "test-unit", "~> 1.2"
 end