CI: Add Rails 8 and drop Rails 6.1 (ohler55#947)

* CI: Add Rails 8

* CI: Drop Rails 6.1

Because Rails 6.1 has reached End of Maintenance
https://rubyonrails.org/2024/10/15/new-maintenance-policy-and-eol-annouments

.github/workflows/CI.yml

@@ -28,34 +28,32 @@ jobs:
           - windows
         gemfile:
           - no_rails
-          - rails_6.1
           - rails_7
           - rails_7.1
           - rails_7.2
+          - rails_8
         exclude:
           - ruby: 2.7
             gemfile: rails_7.2
           - ruby: 3.0
             gemfile: rails_7.2
+          - ruby: 2.7
+            gemfile: rails_8
+          - ruby: 3.0
+            gemfile: rails_8
+          - ruby: 3.1
+            gemfile: rails_8
           - os: macos
             ruby: head
           - os: windows
             ruby: head
-          - os: windows
-            gemfile: rails_6.1
           - os: windows
             gemfile: rails_7
           - os: windows
             gemfile: rails_7.1
           - os: windows
             gemfile: rails_7.2
         include:
-          - ruby: '2.7'
-            gemfile: rails_6 # End of life June 1, 2023
-            os: ubuntu
-          - ruby: '2.7'
-            gemfile: rails_6 # End of life June 1, 2023
-            os: macos
           # - ruby: 'truffleruby'
           #   gemfile: no_rails
           #   os: ubuntu

gemfiles/rails_6.1.gemfile → gemfiles/rails_8.gemfile

@@ -2,7 +2,7 @@
 
 source 'https://rubygems.org'
 
-gem 'rails', '6.1.3.1'
+gem 'rails', '~> 8.0.1'
 gem 'sqlite3'
 gem 'mutex_m'
 gem 'base64'