adding expect and compression plugins by default to the aws_sigv4 plugin

It's expected that this endpoint will be used i most cases for file
uploads, so both plugins will be important to improve throughput and
auth-fail-fast scenarios

lib/httpx/plugins/aws_sigv4.rb

@@ -153,8 +153,10 @@ module HTTPX
           end.new.merge(options)
         end
 
-        def load_dependencies(_klass)
+        def load_dependencies(klass)
           require "openssl"
+          klass.plugin(:expect)
+          klass.plugin(:compression)
         end
       end