fix: 8008 theme duplicate sub-alt-color (@tboex) (monkeytypegame#6879)

### Description

the 8008 theme had a duplicate `--sub-alt-color` set to `#000000`

### Checks

- [ ] Adding quotes?
- [ ] Make sure to include translations for the quotes in the
description (or another comment) so we can verify their content.
- [ ] Adding a language?
- Make sure to follow the [languages
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/LANGUAGES.md)
  - [ ] Add language to `packages/schemas/src/languages.ts`
- [ ] Add language to exactly one group in
`frontend/src/ts/constants/languages.ts`
  - [ ] Add language json file to `frontend/static/languages` 
- [ ] Adding a theme?
- Make sure to follow the [themes
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/THEMES.md)
  - [ ] Add theme to `packages/schemas/src/themes.ts`
  - [ ] Add theme to `frontend/src/ts/constants/themes.ts`
  - [ ] Add theme css file to `frontend/static/themes`
- [ ] Add some screenshot of the theme, especially with different test
settings (colorful, flip colors) to your pull request
- [ ] Adding a layout?
- [ ] Make sure to follow the [layouts
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/LAYOUTS.md)
  - [ ] Add layout to `packages/schemas/src/layouts.ts`
  - [ ] Add layout json file to `frontend/static/layouts` 
- [ ] Adding a font?
- Make sure to follow the [themes
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/FONTS.md)
  - [ ] Add font file  to `frontend/static/webfonts`
  - [ ] Add font to `packages/schemas/src/fonts.ts`
  - [ ] Add font to `frontend/src/ts/constants/fonts.ts`
- [O] Check if any open issues are related to this PR; if so, be sure to
tag them below.
- [O] Make sure the PR title follows the Conventional Commits standard.
(https://www.conventionalcommits.org for more info)
- [O] Make sure to include your GitHub username prefixed with @ inside
parentheses at the end of the PR title.

<!-- label(optional scope): pull request title (@tboex) -->

<!-- I know I know they seem boring but please do them, they help us and
you will find out it also helps you.-->

Author: tboex

frontend/static/themes/8008.css

@@ -3,7 +3,6 @@
   --main-color: #f44c7f;
   --caret-color: #f44c7f;
   --sub-color: #939eae;
-  --sub-alt-color: #000000;
   --sub-alt-color: #2e343d;
   --text-color: #e9ecf0;
   --error-color: #da3333;