Create a new LoadError for missing dependencies

I think that's more correct, because we don't want a potential backtrace
somewhere within those gems, we want the backtrace to lead to this line.

Author: janko

lib/image_processing/mini_magick.rb

@@ -1,8 +1,8 @@
 require "image_processing"
 begin
   require "mini_magick"
-rescue LoadError => e
-  raise e, "ImageProcessing::MiniMagick requires the mini_magick gem. Please add `gem \"mini_magick\", \"~> 5.0\"` to your Gemfile."
+rescue LoadError
+  raise LoadError, "ImageProcessing::MiniMagick requires the mini_magick gem. Please add `gem \"mini_magick\", \"~> 5.0\"` to your Gemfile."
 end
 
 module ImageProcessing

lib/image_processing/vips.rb

@@ -1,8 +1,8 @@
 require "image_processing"
 begin
   require "vips"
-rescue LoadError => e
-  raise e, "ImageProcessing::Vips requires the ruby-vips gem. Please add `gem \"ruby-vips\", \"~> 2.0\"` to your Gemfile."
+rescue LoadError
+  raise LoadError, "ImageProcessing::Vips requires the ruby-vips gem. Please add `gem \"ruby-vips\", \"~> 2.0\"` to your Gemfile."
 end
 
 Vips.block_untrusted(true) if Vips.respond_to?(:block_untrusted) && !ENV["VIPS_BLOCK_UNTRUSTED"]