Bump bundler version to 2.5.15

[thdaraujo]

Motivation / Background

This will remove the following deprecation warning from thor when running tests:

Calling `DidYouMean::SPELL_CHECKERS.merge!(error_name => spell_checker)' has been deprecated. Please call `DidYouMean.correct_error(error_name, spell_checker)' instead.
/opt/hostedtoolcache/Ruby/3.3.4/x64/lib/ruby/gems/3.3.0/gems/bundler-2.2.33/lib/bundler/vendor/thor/lib/thor/error.rb:105: warning: constant DidYouMean::SPELL_CHECKERS is deprecated

Additional information

Checklist

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