Start testing against Ruby 4 in CI

Ruby 4.0.0 release
- https://www.ruby-lang.org/en/news/2025/12/25/ruby-4-0-0-released/
- https://github.com/ruby/ruby/releases/tag/v4.0.0

Upgrade the following to pick up Ruby 4.0 support:
- sqlite3 gem from 2.8.1 to 2.9.0 | https://github.com/sparklemotion/sqlite3-ruby/releases/tag/v2.9.0
- nokogiri gem from 1.18.10 to 1.19.0 | https://github.com/sparklemotion/nokogiri/releases/tag/v1.19.0
- unicode-emoji gem from 4.1.0 to 4.2.0 | https://github.com/janlelis/unicode-emoji/blob/beff6fe9a2935a8c1bd417ae7e775c685d514f2e/CHANGELOG.md#420
- minitest gem from 5.26.0 to 5.27.0 | https://github.com/minitest/minitest/blob/edd37ce7240a645054485b8c470927765e65351b/History.rdoc#label-5.27.0+-2F+2025-12-11

Author: larouxn

.github/workflows/ci.yml

@@ -24,12 +24,15 @@ jobs:
         - gemfiles/rails_8_0.gemfile
         - Gemfile # current minor release
         - gemfiles/rails_main.gemfile
-        ruby: ["3.2", "3.3", "3.4"]
+        ruby: ["3.2", "3.3", "3.4", "4.0"]
         database: [sqlite]
         include:
         - gemfile: "gemfiles/postgresql.gemfile"
           ruby: 3.4
           database: postgres
+        - gemfile: "gemfiles/postgresql.gemfile"
+          ruby: 4.0
+          database: postgres
         exclude:
         - gemfile: gemfiles/rails_main.gemfile
           ruby: 3.2

Gemfile.lock

@@ -152,7 +152,7 @@ GEM
     matrix (0.4.3)
     mini_mime (1.1.5)
     mini_portile2 (2.8.9)
-    minitest (5.26.0)
+    minitest (5.27.0)
     mocha (3.0.1)
       ruby2_keywords (>= 0.0.5)
     net-imap (0.5.12)