Add Github Actions CI with newer ruby versions and updated README

.github/workflows/CI.yml

@@ -0,0 +1,31 @@
+name: Ruby
+
+on: [push]
+
+jobs:
+  test:
+    name: CI-tests
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby:
+          - '3.1'
+          - '3.0'
+          - '2.7'
+          - '2.6'
+          - '2.5'
+          - '2.4'
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+
+      - name: Run tests
+        run: |
+          bundle exec rake jira:generate_public_cert
+          bundle exec rake spec

README.md

@@ -1,6 +1,7 @@
 # JIRA API Gem
 
 [![Code Climate](https://codeclimate.com/github/sumoheavy/jira-ruby.svg)](https://codeclimate.com/github/sumoheavy/jira-ruby)
+[![Build Status](https://github.com/sumoheavy/jira-ruby/actions/workflows/CI.yml/badge.svg)](https://github.com/sumoheavy/jira-ruby/actions/workflows/CI.yml)
 
 This gem provides access to the Atlassian JIRA REST API.