feat: add support for highlight .cpy and .cpb files as COBOL

[gustavosimon]

No description provided.

[Copilot]

Pull request overview

This PR adds support for recognizing .cpy and .cpb file extensions as COBOL files in the Rouge syntax highlighter. These are standard COBOL copybook file extensions commonly used in COBOL development. The changes enable the lexer to properly identify and highlight these file types alongside the existing .cob and .cbl extensions.

Key changes:

• Added .cpy and .cpb to the list of recognized COBOL file extensions
• Added corresponding test coverage for the new file extensions

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
lib/rouge/lexers/cobol.rb	Updated filenames declaration to include *.cpy and *.cpb extensions
spec/lexers/cobol_spec.rb	Added test assertions to verify filename guessing works for .cpy and .cpb files

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After thoroughly reviewing the changes, I found no issues with this pull request. The implementation is clean, follows the established patterns in the codebase, and properly adds both the lexer support and corresponding test coverage. The .cpy (copybook) and .cpb (copybook) extensions are legitimate COBOL file extensions used in the COBOL community, particularly for files containing reusable code snippets that are copied into other programs during compilation.

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[gustavosimon]

@tancnle @pyrmont maybe you can take a look in this PR?

[pyrmont]

I'm sorry, @gustavosimon. I'm no longer a maintainer on this project.