Update root Gemfile bundler version to resolve multiple warnings #22

Job	Run time
Tests (Ruby 3.0, Gemfile)	2m 2s
Tests (Ruby 3.0, gemfiles/rails_7_0_propshaft.gemfile)	1m 58s
Tests (Ruby 3.0, gemfiles/rails_7_1_propshaft.gemfile)	20s
Tests (Ruby 3.0, gemfiles/rails_7_0_sprockets.gemfile)	2m 17s
Tests (Ruby 3.0, gemfiles/rails_7_1_sprockets.gemfile)	19s
Tests (Ruby 3.1, Gemfile)	24s
Tests (Ruby 3.1, gemfiles/rails_7_0_propshaft.gemfile)	23s
Tests (Ruby 3.1, gemfiles/rails_7_1_propshaft.gemfile)	21s
Tests (Ruby 3.1, gemfiles/rails_main_propshaft.gemfile)	24s
Tests (Ruby 3.1, gemfiles/rails_7_0_sprockets.gemfile)	19s
Tests (Ruby 3.1, gemfiles/rails_7_1_sprockets.gemfile)	23s
Tests (Ruby 3.1, gemfiles/rails_main_sprockets.gemfile)	24s
Tests (Ruby 3.2, Gemfile)	50s
Tests (Ruby 3.2, gemfiles/rails_7_0_propshaft.gemfile)	53s
Tests (Ruby 3.2, gemfiles/rails_7_1_propshaft.gemfile)	57s
Tests (Ruby 3.2, gemfiles/rails_main_propshaft.gemfile)	1m 3s
Tests (Ruby 3.2, gemfiles/rails_7_0_sprockets.gemfile)	1m 1s
Tests (Ruby 3.2, gemfiles/rails_7_1_sprockets.gemfile)	58s
Tests (Ruby 3.2, gemfiles/rails_main_sprockets.gemfile)	1m 6s
Tests (Ruby 3.3, Gemfile)	59s
Tests (Ruby 3.3, gemfiles/rails_7_0_propshaft.gemfile)	59s
Tests (Ruby 3.3, gemfiles/rails_7_1_propshaft.gemfile)	58s
Tests (Ruby 3.3, gemfiles/rails_main_propshaft.gemfile)	1m 10s
Tests (Ruby 3.3, gemfiles/rails_7_0_sprockets.gemfile)	1m 4s
Tests (Ruby 3.3, gemfiles/rails_7_1_sprockets.gemfile)	1m 1s
Tests (Ruby 3.3, gemfiles/rails_main_sprockets.gemfile)	1m 3s
	23m 36s

Provide feedback