Update dotenv-rails requirement from ~> 2.2.1 to >= 2.2.1, < 2.6.0

Updates the requirements on [dotenv-rails](https://github.com/bkeepers/dotenv) to permit the latest version.
- [Release notes](https://github.com/bkeepers/dotenv/releases)
- [Changelog](https://github.com/bkeepers/dotenv/blob/master/Changelog.md)
- [Commits](https://github.com/bkeepers/dotenv/commits/v2.5.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

dotenv-rails-safe.gemspec

@@ -34,7 +34,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "dotenv-rails", '~> 2.2.1'
+  spec.add_dependency "dotenv-rails", '>= 2.2.1', '< 2.6.0'
 
   spec.add_development_dependency "bundler", "~> 1.13"
   spec.add_development_dependency "rake", "~> 10.0"