Adds Contributing.md #56

Job	Run time
Tests (Ruby 3.1, gemfiles/rails_6_1.gemfile)	1m 32s
Tests (Ruby 3.1, gemfiles/rails_7_0.gemfile)	53s
Tests (Ruby 3.1, gemfiles/rails_7_1.gemfile)	1m 3s
Tests (Ruby 3.1, gemfiles/rails_7_2.gemfile)	1m 12s
Tests (Ruby 3.2, gemfiles/rails_6_1.gemfile)	1m 37s
Tests (Ruby 3.2, gemfiles/rails_7_0.gemfile)	57s
Tests (Ruby 3.2, gemfiles/rails_7_1.gemfile)	1m 7s
Tests (Ruby 3.2, gemfiles/rails_7_2.gemfile)	1m 17s
Tests (Ruby 3.2, gemfiles/rails_8_0.gemfile)	1m 2s
Tests (Ruby 3.2, gemfiles/rails_main.gemfile)	1m 12s
Tests (Ruby 3.3, gemfiles/rails_7_0.gemfile)	59s
Tests (Ruby 3.3, gemfiles/rails_7_1.gemfile)	1m 9s
Tests (Ruby 3.3, gemfiles/rails_7_2.gemfile)	1m 24s
Tests (Ruby 3.3, gemfiles/rails_8_0.gemfile)	1m 14s
Tests (Ruby 3.3, gemfiles/rails_main.gemfile)	1m 6s
Tests (Ruby 3.4, gemfiles/rails_7_1.gemfile)	1m 11s
Tests (Ruby 3.4, gemfiles/rails_7_2.gemfile)	1m 5s
Tests (Ruby 3.4, gemfiles/rails_8_0.gemfile)	1m 2s
Tests (Ruby 3.4, gemfiles/rails_main.gemfile)	1m 8s
	22m 10s

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