editorconfig: properly resolve UTF-8 validation workaround

[trueNAHO]

The editorconfig issue from #2035 (comment) should be properly resolved in order to fix up the following two different workarounds:

• On the master branch:

  commit 1acea29f68227fdc120c8889f906ee0fa68a70d2
  Author: stylix-automation[bot] <190860676+stylix-automation[bot]@users.noreply.github.com>
  Date:   2025-12-03 21:59:32 +0100
  
      flake: update all inputs (#2035)
      
      Link: https://github.com/nix-community/stylix/pull/2035
      
      Reviewed-by: 0xda157 <da157@voidq.com>
      Co-authored-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
      Co-authored-by: 0xda157 <da157@voidq.com>
      Reviewed-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
  
  diff --git a/.editorconfig b/.editorconfig
  index cef70f21..613d5c37 100644
  --- a/.editorconfig
  +++ b/.editorconfig
  @@ -6,7 +6,6 @@ end_of_line = lf
   indent_style = space
   insert_final_newline = true
   trim_trailing_whitespace = true
  -charset = utf-8
   
   [*.{diff,patch}]
   end_of_line = unset

• On the release-25.11 branch:

  commit 6d5708ee0c229eaaadf502a1198feaeb23280843
  Author: 0xda157 <da157@voidq.com>
  Date:   2025-12-02 06:40:02 -1000
  
      flake: use 25.11 branch of dependencies (#2026)
      
      Link: https://github.com/nix-community/stylix/pull/2026
      
      Reviewed-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
  
  diff --git a/.editorconfig b/.editorconfig
  index cef70f21..e814d0f4 100644
  --- a/.editorconfig
  +++ b/.editorconfig
  @@ -6,7 +6,7 @@ end_of_line = lf
   indent_style = space
   insert_final_newline = true
   trim_trailing_whitespace = true
  -charset = utf-8
  +charset = unset
   
   [*.{diff,patch}]
   end_of_line = unset

CC: @0xda157