Update Bundler to 2.5.21 and truffleruby to 24.1.0 #84

Job	Run time
RubyGems on Ubuntu (3.0)	5s
RubyGems on Ubuntu (3.1)	14s
RubyGems on Ubuntu (3.2)	8s
RubyGems on macOS (3.0)	11s
RubyGems on macOS (3.1)	14s
RubyGems on macOS (3.2)	13s
RubyGems on Windows (3.0)	3m 27s
RubyGems on Windows (3.1)	4m 6s
RubyGems on Windows (3.2)	3m 41s
RubyGems on Ubuntu (jruby-9.4)	37s
RubyGems on Ubuntu (truffleruby-24)	18s
RubyGems on Windows (mswin)	2m 41s
RubyGems on Ubuntu (ruby-head)	6s
RubyGems on Ubuntu (truffleruby-head)	18s
	16m 19s

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