Bump dependencies.

Author: ioquatix

protocol-http2.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
 	spec.required_ruby_version = '~> 2.5'
 
 	spec.add_dependency "protocol-hpack", "~> 1.4"
-	spec.add_dependency "protocol-http", "~> 0.15"
+	spec.add_dependency "protocol-http", "~> 0.18"
 
 	spec.add_development_dependency "covered"
 	spec.add_development_dependency "bake-bundler"