fix: incorrect mime type parsing

spec/responsible/response_spec.cr

@@ -43,6 +43,18 @@ describe Responsible::Response do
       end
       error_block_executed.should be_true
     end
+
+    it "correctly parses content types" do
+      WebMock.stub(:get, "www.example.com").to_return(
+        headers: { "Content-Type" => "application/json; charset=UTF-8" },
+        body: <<-JSON
+          {"value":"foo"}
+        JSON
+      )
+      response = ~HTTP::Client.get("www.example.com") 
+      result = response.parse_to NamedTuple(value: String)
+      result[:value].should eq("foo")
+    end
   end
 
   describe "#parse_to?" do

src/responsible/response.cr

@@ -1,4 +1,5 @@
 require "json"
+require "mime/media_type"
 require "./response_interface"
 require "./response_type"
 
@@ -55,17 +56,16 @@ class Responsible::Response
   def parse_to(x : T.class, ignore_response_code = @in_handler, &block : Exception -> U) : T | U forall T, U
     raise Error.from(self) unless success? || ignore_response_code
 
-    content_type = headers["content-type"].split(' ').first.downcase
+    mime_type = MIME::MediaType.parse headers["Content-Type"]
 
-    case content_type
-    when "application/json"
+    if mime_type.media_type == "application/json"
       begin
         T.from_json(@response.body? || @response.body_io)
       rescue e
         yield e
       end
     else
-      raise Error.new "unsupported content type (#{content_type})"
+      raise Error.new "unsupported MIME type (#{mime_type})"
     end
   end