gemspec: update dependencies.

Gemfile

@@ -1,9 +1,4 @@
 source 'https://rubygems.org'
 
-git_source(:github) do |repo_name|
-  repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
-  "https://github.com/#{repo_name}.git"
-end
-
 gemspec
-gem "dtext_rb", github: "r888888888/dtext_rb"
+gem "dtext_rb", git: "https://github.com/evazion/dtext_rb"

ruby-booru.gemspec

@@ -22,16 +22,16 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '~> 2.4'
 
-  spec.add_runtime_dependency "activesupport", "~> 5"
-  spec.add_runtime_dependency "addressable", "~> 2.5"
-  spec.add_runtime_dependency "connection_pool", "~> 2.2"
+  spec.add_runtime_dependency "activesupport", "~> 6"
+  spec.add_runtime_dependency "addressable", "~> 2"
+  spec.add_runtime_dependency "connection_pool", "~> 2"
   spec.add_runtime_dependency "dotenv", "~> 2"
-  spec.add_runtime_dependency "dtext_rb", "~> 1.6"
-  spec.add_runtime_dependency "http", "~> 3"
+  spec.add_runtime_dependency "dtext_rb", "~> 1"
+  spec.add_runtime_dependency "http", "~> 4"
   spec.add_runtime_dependency "retriable", "~> 3"
 
-  spec.add_development_dependency "bundler", "~> 1.14"
-  spec.add_development_dependency "rake", "~> 12.0"
+  spec.add_development_dependency "bundler", "~> 2"
+  spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "pry", "~> 0.10"
   spec.add_development_dependency "pry-byebug", "~> 3.4"
   spec.add_development_dependency "minitest", "~> 5.0"