Support for Ruby 4

[nodeg]

Currently, when trying to update my gems, I get the following error:

$ gem update
Updating installed gems
Updating clamp
ERROR:  Error installing clamp:
        clamp-1.3.3 requires Ruby version >= 2.5, < 4. The current ruby version is 4.0.1.

which is due to

clamp/clamp.gemspec

Line 26 in e4ff8ef

s.required_ruby_version = ">= 2.5", "< 4"