Add support for Gitea Actions

[silverwind]

Add support for Gitea Actions.

Both GITHUB_ACTIONS and GITEA_ACTIONS are present, with the former being a compatibilty solution, the latter is the true identifier.

It supports 16 colors and true color, but not 256 color currently. I plan to fix 256 color and will follow up here once it's done.

[silverwind]

The xo failure seems unrelated.

[silverwind]

go-gitea/gitea#25401 adds 256 color support so now full 16m color is supported and the condition is simplified.

[silverwind]

Tried updating xo, and that seems to at least not make it crash anymore. Locally it outputs a number of issues. All are unrelated to this PR:

  index.js:60:1
  ⚠  60:1   Function _supportsColor has a complexity of 37. Maximum allowed is 20.                            complexity

  test.js:24:1
  ⚠  24:1   Unexpected fixme comment: FIXME.                                                                  no-warning-comments

  index.d.ts:3:18
  ✖   3:18  Use a type instead of an interface.                                                               @typescript-eslint/consistent-type-definitions
  ✖  24:18  Use a type instead of an interface.                                                               @typescript-eslint/consistent-type-definitions

  browser.js:6:12
  ✖   6:12  Optional chainings are not supported until Node.js 14.0.0. The configured version range is >=12.  n/no-unsupported-features/es-syntax

  index.test-d.ts:3:1
  ✖   3:1   Imports "Options" and "ColorInfo" are only used as types.                                         @typescript-eslint/consistent-type-imports

[sindresorhus]

Can you do a PR to https://github.com/chalk/chalk/tree/main/source/vendor/supports-color too?

[silverwind]

Sure, I can try.

[silverwind]

chalk/chalk#603 for vendor update in chalk.