Remove deprecated option `bottle :unneeded` (#146)

## Remove deprecated option `bottle :unneeded`

### Summary

- `bottle :unneeded` is deprecated
- `bottle :unneeded` was removed from brew formula

### Links

- [How to handle bottle :unneeded deprecation for external taps](https://github.com/Homebrew/discussions/discussions/2311)
- [Bottle all bottle :unneeded](https://github.com/Homebrew/homebrew-core/issues/75943)
- [formula_auditor: don't allow bottle :unneeded in core](https://github.com/Homebrew/brew/pull/11239)

Reviewed-on: https://gitea.com/gitea/homebrew-gitea/pulls/146
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: Norwin <noerw@noreply.gitea.io>
Co-authored-by: GAG <gag@noreply.gitea.io>
Co-committed-by: GAG <gag@noreply.gitea.io>

gitea.rb

@@ -37,7 +37,6 @@ class Gitea < Formula
       using: @@using
 
   conflicts_with "gitea-head", because: "both install gitea binaries"
-  bottle :unneeded
   def install
     if stable.using.blank?
       filename = Gitea.class_variable_get("@@filename")