Only use UnboundMethod#bind_call if it is available

This allows tests to pass on Ruby 2.4-2.6. Fixes #19

Author: jeremyevans

lib/uri/rfc2396_parser.rb

@@ -322,8 +322,14 @@ def unescape(str, escaped = @regexp[:ESCAPED])
  end
 
  @@to_s = Kernel.instance_method(:to_s)
- def inspect
- @@to_s.bind_call(self)
+ if @@to_s.respond_to?(:bind_call)
+ def inspect
+ @@to_s.bind_call(self)
+ end
+ else
+ def inspect
+ @@to_s.bind(self).call
+ end
  end
 
  private

lib/uri/rfc3986_parser.rb

@@ -79,8 +79,14 @@ def join(*uris) # :nodoc:
  end
 
  @@to_s = Kernel.instance_method(:to_s)
- def inspect
- @@to_s.bind_call(self)
+ if @@to_s.respond_to?(:bind_call)
+ def inspect
+ @@to_s.bind_call(self)
+ end
+ else
+ def inspect
+ @@to_s.bind(self).call
+ end
  end
 
  private