Mark .{1..9} as generic file-extensions

[Alhadis]

Description

Successor of #4258, which makes use of Linguist's new generic extensions feature. To recap:

Many files on GitHub receive an incorrect classification of "Roff", simply because their filenames end in a numeric suffix:

Gemfile-3.0.3
GFDL-1.2
AFL-1.2
mkfontscale-1.1.1

Change-logs and version-numbers are particularly problematic examples of these. The ValveSoftware/steam-runtime, for instance, was shown as 72.8% Roff (until I fixed it), because of three license files with version-numbers. haskell-CI/haskell-ci was another example (until fixed). You can find those and more by checking GitHub's list of trending Roff repositories.

Checklist:

• I am adding new or changing current functionality
  • I have added or updated the tests for the new or changed functionality.

[Alhadis]

@lildude Once this gets merged, and with your blessing, I'll follow-up with a PR to move the generic extensions list to its own file (lib/linguist/generic.yml).

[smola]

Nice easter eggs here 😄

[lildude]

LGTM

[lildude]

Once this gets merged, and with your blessing, I'll follow-up with a PR to move the generic extensions list to its own file (lib/linguist/generic.yml).

Go for it. 🙇‍♂️

[Alhadis]

Done. 👍 See #5070.