Updated required_ruby_version

So the gem isn't limited to v2, which is EOL

sketch.gemspec

@@ -2,6 +2,7 @@
 $:.push File.expand_path("../lib", __FILE__)
 
 Gem::Specification.new do |s|
+    spec = s
   s.name        = "sketch"
   s.version     = '0.4'
   s.authors     = ["Brandon Fosdick"]
@@ -17,9 +18,8 @@ Gem::Specification.new do |s|
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths = ["lib"]
 
-    s.required_ruby_version = '~> 2'
+    spec.required_ruby_version = '>= 2'
 
-    spec = s
     spec.add_dependency 'geometry', '~> 6.6'
 
     spec.add_development_dependency "bundler", "~> 2"