move CI to Buildkite

Author: joshuay03

.buildkite/pipeline.yml

@@ -0,0 +1,37 @@
+steps:
+  - label: ":ruby: Ruby 3.0"
+    image: "ruby:3.3"
+    commands:
+      - bundle install
+      - bundle exec rake
+
+  - label: ":ruby: Ruby 3.1"
+    image: "ruby:3.4"
+    commands:
+      - bundle install
+      - bundle exec rake
+
+  - label: ":ruby: Ruby 3.2"
+    image: "ruby:3.4"
+    commands:
+      - bundle install
+      - bundle exec rake
+
+  - label: ":ruby: Ruby 3.3"
+    image: "ruby:3.4"
+    commands:
+      - bundle install
+      - bundle exec rake
+
+  - label: ":ruby: Ruby 3.4"
+    image: "ruby:3.4"
+    commands:
+      - bundle install
+      - bundle exec rake
+
+  - label: ":ruby: Ruby head"
+    image: "rubylang/ruby:master-dev"
+    commands:
+      - apt-get update && apt-get install -y libyaml-dev
+      - bundle install
+      - bundle exec rake

.github/workflows/docs.yml

@@ -8,14 +8,13 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-
     steps:
       - uses: actions/checkout@v4
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: head
           bundler-cache: true
 
       - name: Generate YARD docs

.github/workflows/tests.yml

@@ -1,7 +1,7 @@
 # RedBlackTree
 
 ![Version](https://img.shields.io/gem/v/red-black-tree)
-![Build](https://img.shields.io/github/actions/workflow/status/joshuay03/red-black-tree/.github/workflows/tests.yml?branch=main)
+![Build](https://badge.buildkite.com/6ccbd68c23960899d1deafdb4cfaa96f1e8c04ad6e198e193b.svg)
 
 [Red-black tree](https://en.wikipedia.org/wiki/Red%E2%80%93black_tree) data structure for Ruby.