Make Lint/DeprecatedClassMethods aware of ENV.clone and ENV.dup

[koic]

Follow up ruby/ruby#4557.

This PR makes Lint/DeprecatedClassMethods aware of ENV.clone and ENV.dup.
This update is based on the following behaviors:

% ruby -v
ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-darwin19]

% ruby -we 'ENV.clone'
-e:1: warning: ENV.clone is deprecated; use ENV.to_h instead

% ruby -e 'ENV.dup'
-e:1:in `dup': Cannot dup ENV, use ENV.to_h to get a copy of ENV as a hash (TypeError)
        from -e:1:in `<main>'

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Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.