Pick up Transitional Type Aliases

[toddsundsted]

This change explicitly requires dependent code so that transitional types aliases (and deprecation warnings) are included. Paves the way for the release of 0.35.0.

See: crystal-lang/crystal#8886 (specifically the type aliases).

Description of the Change

Simply explicitly requires dependent code. When not present, building against the currently nightly crystal build results in errors like the following (including when running the specs):

...
...
In src/kemal/helpers/helpers.cr:135:8
 135 | File.open(file_path) do |file|
            ^---
Error: instantiating 'File.class#open(String)'

In src/kemal/helpers/helpers.cr:143:7
 143 | Gzip::Writer.open(env.response) do |deflate|
       ^-----------
Error: undefined constant Gzip::Writer

Benefits

This change does not affect existing functionality, but avoids problems when building against the current nightly crystal build, and presumably 0.35.0 when it's released.

[sdogruyol]

Thanks @toddsundsted 🙏