Add ruby version

Author: drwl

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: ['2.4.x', '2.5.x', '2.6.x']
+        ruby: ['2.6.x']
 
     steps:
       - name: Checkout
@@ -26,8 +26,7 @@ jobs:
 
       - name: Update System
         run: |
-          gem update --system
-          gem update bundler --quiet
+          gem update --system --no-document
 
       - name: Bundle install for Annotate models
         run: |

spec/integration/rails_6.0.2.1/Gemfile

@@ -1,6 +1,8 @@
 source 'https://rubygems.org'
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
+ruby '2.6.5'
+
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 6.0.2', '>= 6.0.2.1'
 # Use sqlite3 as the database for Active Record