Align mdl constraint with Ruby 3.1 compatibility

Update mdl development dependency from ~> 0.13 to ~> 0.14, keep Ruby 3.1
support intact, and document the dependency policy change in CHANGELOG.

Author: evolve75

CHANGELOG.md

@@ -43,6 +43,8 @@ Changes section to scan for breaking or behavioral changes.
 * Refresh development dependencies with a conservative lockfile update by
   upgrading `rdoc` from `7.1.0` to `7.2.0` within existing version
   constraints.
+* Raise the `mdl` development dependency constraint from `~> 0.13` to
+  `~> 0.14` while retaining Ruby 3.1 compatibility.
 
 ### 3.0.0pre / 2026-02-09
 

Gemfile.lock

@@ -120,7 +120,7 @@ DEPENDENCIES
   awesome_bot (~> 1.20)
   bundler (~> 2.6)
   bundler-audit (~> 0.9)
-  mdl (~> 0.13)
+  mdl (~> 0.14)
   rake (~> 13.3)
   rdoc (~> 7.1)
   rspec (~> 3.13)

rubytree.gemspec

@@ -76,7 +76,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rspec', '~> 3.13'
   s.add_development_dependency 'rtagstask', '~> 0.0'
   s.add_development_dependency 'awesome_bot', '~> 1.20'
-  s.add_development_dependency 'mdl', '~> 0.13'
+  s.add_development_dependency 'mdl', '~> 0.14'
   s.add_development_dependency 'rubocop', '~> 1.84'
   s.add_development_dependency 'rubocop-rake', '~> 0.7'
   s.add_development_dependency 'rubocop-rspec', '~> 3.0'