Bump Ruby I18n requirement

Require 1.9, the first version tested against Ruby 3.1

Close #1097

Ref: https://github.com/ruby-i18n/i18n/releases?page=2

Author: tagliala

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Upcoming 7.0.0.alpha
 
+- Require Ruby >= 3.1 and I18n >= 1.9
 - **Potential breaking change**: Fix USDC decimals places from 2 to 6
 
 ## 6.19.0

money.gemspec

@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
   s.license     = "MIT"
 
   s.add_dependency "bigdecimal"
-  s.add_dependency 'i18n', [">= 0.6.4", '<= 2']
+  s.add_dependency 'i18n', "~> 1.9"
 
   s.add_development_dependency "bundler"
   s.add_development_dependency "rake"