cask/exceptions: Actually print actual hash

Library/Homebrew/cask/exceptions.rb

@@ -184,7 +184,7 @@ module Cask
     def to_s
       <<~EOS
         Cask '#{token}' requires a checksum:
-          #{Formatter.identifier('sha256 "#{actual}"')}
+          #{Formatter.identifier("sha256 \"#{actual}\"")}
       EOS
     end
   end

Library/Homebrew/test/cask/verify_spec.rb

@@ -31,7 +31,7 @@ module Cask
         let(:expected_sha256) { nil }
 
         it "raises an error" do
-          expect { verification }.to raise_error CaskSha256MissingError
+          expect { verification }.to raise_error(CaskSha256MissingError, /sha256 "#{computed_sha256}"/)
         end
       end
 
@@ -39,7 +39,7 @@ module Cask
         let(:expected_sha256) { "" }
 
         it "raises an error" do
-          expect { verification }.to raise_error CaskSha256MissingError
+          expect { verification }.to raise_error(CaskSha256MissingError, /sha256 "#{computed_sha256}"/)
         end
       end