Support Rails 7.2

[mohammed-io]

• Supporting Rails 7.2
• Dropping Ruby 2 support in Rubocop and Gemspec (3.0.0 is minimum now)

[mohammed-io]

The next version will be 8.0 tho.

[mohammed-io]

@marcqualie looks like one issue left for the test

            /opt/hostedtoolcache/Ruby/3.0.7/x64/lib/ruby/3.0.0/rubygems/resolver/molinillo/lib/molinillo/resolution.rb:317:in `raise_error_unless_state': Unable to satisfy the following requirements: (Gem::Resolver::Molinillo::VersionConflict)
            
            - `activesupport (= 7.2.1)` required by `user-specified dependency`
            - `activesupport (>= 5.0.0)` required by `rails-dom-testing-2.2.0`
            ```

[mohammed-io]

I though some of errors due to Ruby version mismatch. It looks like it didn't fix the issue. Should I revert the version change?

[mohammed-io]

Suggested change

	TargetRubyVersion: 3.0
	TargetRubyVersion: 2.6

[mohammed-io]

Suggested change

	Dir.glob("#{path}/lib/diffcrypt/tasks/**/*.rake").each { |f| load f }
	Dir.glob("#{path}/lib/diffcrypt/tasks/**/*.rake").sort.each { |f| load f }

[mohammed-io]

Suggested change

	spec.required_ruby_version = Gem::Requirement.new('>= 3.0.0')
	spec.required_ruby_version = Gem::Requirement.new('>= 2.6.0')