Use IndifferentHash class instead of method

[dmathieu]

The indifferent_params method doesn't exist anymore in Sinatra 2.0 (See sinatra/sinatra@44c3cb8#diff-f2bc16b264ca20ca842cf15d82960d34 ).

cc @bigkevmcd

[brandur]

Thanks for the tests! This looks good to me (also, this makes way more sense as a class method so I'm relatively glad to see that Sinatra changed it even if it's annoying).

Do you know if @gudmundur or someone else can run a release? I haven't done one in a while.

[gudmundur]

Thanks @dmathieu. Will this work with Sinatra 1? I know the class exists, but I'm not sure it'll behave the same way.

If this doesn't work with Sinatra 1, we can either:

1. Add a support method that'll detect whether the method or class should be used. Thus support both versions.
2. Drop support for Sinatra 1, and cut a major version of Pliny.

My personal preference would be to support both, with a comment about dropping some code in the future once we go Sinatra 2 only.

[dmathieu]

Very good point. I've just added support for both.

[gudmundur]

@dmathieu Nice work. This looks good to me. @brandur does this seem solid to you as well?

[brandur]

Yeah, looks good to me! Thanks @dmathieu, and nice catch on that one @gudmundur.