Allow using bundler 4.x

Fix: #405

Rails nightly CI is currently broken because Ruby 3.5/4.0 ships with bundler 4.0.0.

Author: byroot

gemspec.yml

@@ -18,4 +18,4 @@ required_rubygems_version: ">= 1.8.0"
 
 dependencies:
   thor: "~> 1.0"
-  bundler: ">= 1.2.0, < 3"
+  bundler: ">= 1.2.0"