fix(client): remove external prop on 'donate' link

[kelvinsanchez15]

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)
• My pull request targets the main branch of freeCodeCamp.
• All the files I changed are in the same world language, for example: only English changes, or only Chinese changes, etc.

Closes #41016

[gitpod-io]

[naomi-lgbt]

Testing locally, I can confirm this resolves the issue of /espanol being removed from the donation redirect.

@kelvinsanchez15 I'll generate a suggestion to resolve the linting error momentarily.

[naomi-lgbt]

Suggestion tool is not cooperating.

Replace:

          <Link
            className='nav-link'
            key='donate'
            sameTab={false}
            to='/donate'
          >
            {t('buttons.donate')}
          </Link>

With:

          <Link className='nav-link' key='donate' sameTab={false} to='/donate'>
            {t('buttons.donate')}
          </Link>

[kelvinsanchez15]

Thanks @nhcarrigan as soon as I have some time I will configure a proper fCC local instance.

[naomi-lgbt]

Looks good to me.