prepare for base64 being removed from default gems

.simplecov

@@ -6,4 +6,5 @@ SimpleCov.start do
   add_filter "/integration_tests/"
   add_filter "/regression_tests/"
   add_filter "/lib/httpx/plugins/internal_telemetry.rb"
+  add_filter "/lib/httpx/base64.rb"
 end

lib/httpx/base64.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+if RUBY_VERSION < "3.3.0"
+  require "base64"
+elsif !defined?(Base64)
+  module HTTPX
+    # require "base64" will not be a default gem after ruby 3.4.0
+    module Base64
+      module_function
+
+      def decode64(str)
+        str.unpack1("m")
+      end
+
+      def strict_encode64(bin)
+        [bin].pack("m0")
+      end
+
+      def urlsafe_encode64(bin, padding: true)
+        str = strict_encode64(bin)
+        str.chomp!("==") or str.chomp!("=") unless padding
+        str.tr!("+/", "-_")
+        str
+      end
+    end
+  end
+end

lib/httpx/plugins/auth/basic.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "base64"
+require "httpx/base64"
 
 module HTTPX
   module Plugins

lib/httpx/plugins/auth/ntlm.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "base64"
+require "httpx/base64"
 require "ntlm"
 
 module HTTPX

lib/httpx/plugins/auth/socks5.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "base64"
-
 module HTTPX
   module Plugins
     module Authentication

lib/httpx/plugins/h2c.rb

@@ -13,7 +13,6 @@ module HTTPX
 
       class << self
         def load_dependencies(klass)
-          require "base64"
           klass.plugin(:upgrade)
         end
 

lib/httpx/plugins/proxy/http.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require "base64"
-
 module HTTPX
   module Plugins
     module Proxy

lib/httpx/resolver/https.rb

@@ -4,6 +4,7 @@ require "resolv"
 require "uri"
 require "cgi"
 require "forwardable"
+require "httpx/base64"
 
 module HTTPX
   class Resolver::HTTPS < Resolver::Resolver