switch CI to GitHub Actions

Author: afeld

.github/workflows/ci.yml

@@ -0,0 +1,35 @@
+name: CI
+
+on: push
+
+jobs:
+  rspec:
+    name: RSpec
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.0.0
+          bundler-cache: true
+
+      - name: Configure Git
+        run: |
+          git config --global user.email "tester@example.com"
+          git config --global user.name "Sally Tester"
+
+      - name: Run RSpec
+        run: bundle exec rspec
+
+  shellcheck:
+    name: ShellCheck
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Run ShellCheck
+        uses: ludeeus/action-shellcheck@master

.travis.yml

@@ -1,4 +1,4 @@
-# Git Plugins [![Build Status](https://travis-ci.org/afeld/git-plugins.svg?branch=travis)](https://travis-ci.org/afeld/git-plugins)
+# Git Plugins
 
 A community collection of Git plugins. Browse [the scripts](bin) to see what's included.
 
@@ -47,7 +47,7 @@ export PATH=path/to/git-plugins/bin:$PATH
 
 ## Aliases
 
-The plugin names intentionally favor descriptiveness over terseness, but you should make shortcuts for yourself that make sense for you.  You can see some examples in the `[alias]` section of [afeld/dotfiles](https://github.com/afeld/dotfiles/blob/master/gitconfig).  To add a new shortcut:
+The plugin names intentionally favor descriptiveness over terseness, but you should make shortcuts for yourself that make sense for you. You can see some examples in the `[alias]` section of [afeld/dotfiles](https://github.com/afeld/dotfiles/blob/master/gitconfig). To add a new shortcut:
 
 ```bash
 git config --global alias.SHORT LONG
@@ -75,12 +75,12 @@ git config --global alias.pr create-pull-request
 
 ## See Also
 
-* [Official GitHub CLI](https://cli.github.com/)
-* [Git Extras](https://github.com/tj/git-extras)
-* [EasyGit](https://people.gnome.org/~newren/eg/)
-* [ghi](https://github.com/stephencelis/ghi)
-* [git-flow](https://github.com/nvie/gitflow)
-* [git-setup](https://github.com/afeld/git-setup)
-* [hub](http://hub.github.com/)
-* [HubFlow](http://datasift.github.io/gitflow/)
-* [Legit](http://www.git-legit.org/)
+- [Official GitHub CLI](https://cli.github.com/)
+- [Git Extras](https://github.com/tj/git-extras)
+- [EasyGit](https://people.gnome.org/~newren/eg/)
+- [ghi](https://github.com/stephencelis/ghi)
+- [git-flow](https://github.com/nvie/gitflow)
+- [git-setup](https://github.com/afeld/git-setup)
+- [hub](http://hub.github.com/)
+- [HubFlow](http://datasift.github.io/gitflow/)
+- [Legit](http://www.git-legit.org/)