[ruby/erb] url_encode: use CGI.escapeURIComponent

(https://github.com/ruby/erb/pull/23)

Ref: https://github.com/ruby/cgi/pull/26

This native implementation is much faster
and available in `cgi 0.3.3`.

https://github.com/ruby/erb/commit/2d90e9b010

lib/erb.gemspec

@@ -27,5 +27,7 @@ Gem::Specification.new do |spec|
   spec.executables   = ['erb']
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'cgi'
+  spec.required_ruby_version = ">= 2.7.0"
+
+  spec.add_dependency 'cgi', '>= 0.3.3'
 end

lib/erb.rb

@@ -1019,9 +1019,7 @@ class ERB
     #   Programming%20Ruby%3A%20%20The%20Pragmatic%20Programmer%27s%20Guide
     #
     def url_encode(s)
-      s.to_s.b.gsub(/[^a-zA-Z0-9_\-.~]/n) { |m|
-        sprintf("%%%02X", m.unpack1("C"))
-      }
+      CGI.escapeURIComponent(s.to_s)
     end
     alias u url_encode
     module_function :u