Remove unnecessary "require" statements

src/mangadex/api.cr

@@ -1,4 +1,3 @@
-require "http/client"
 require "json"
 require "csv"
 require "../rename"

src/plugin/plugin.cr

@@ -1,6 +1,5 @@
 require "duktape/runtime"
 require "myhtml"
-require "http"
 require "xml"
 
 class Plugin