Fix compatibility with rspec 3.3

spec/args/input_file_spec.rb

@@ -14,7 +14,7 @@ describe Squib::Args::InputFile do
 
     it 'raises on non-existent file' do
       args = {file: 'foo.rb'}
-      expect { ifile.load!(args, expand_by: 1) }.to raise_error
+      expect { ifile.load!(args, expand_by: 1) }.to raise_error("File #{File.expand_path('foo.rb')} does not exist!")
     end
 
   end

spec/spec_helper.rb

@@ -61,6 +61,7 @@ def scrub_hex(str)
      .gsub(/#<Cairo::Matrix:.*>/,'Matrix')
      .gsub(/#<RSVG::Handle.*>/,'RSVG::Handle')
      .gsub(/#<RSpec::Mocks::Double:.*>/,'MockDouble')
+     .gsub(/#<Double .*>/,'MockDouble')
      .gsub(/RGB:\w{1,8}/,'RGB:')
 end