chore(ui): improve svg icon margin consistency (#7172)
* followup to https://codeberg.org/forgejo/forgejo/pulls/7031#issuecomment-2868277: no visible changes
* followup to https://codeberg.org/forgejo/forgejo/pulls/6963: apply a small margin to the icon
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7172
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: 0ko <0ko@noreply.codeberg.org>
Co-committed-by: 0ko <0ko@noreply.codeberg.org>