Fix#3638
This is a manual Forgejo-specific version of the Gitea PR https://github.com/go-gitea/gitea/pull/30862. The weekly Forgejo PR #3772 could not cherry-pick this commit due to conflicts (eg subsequent CodeSpell changes).
Only occurs with Webkit in Safari over eg `http://192..`. (not localhost).
See https://webkit.org/blog/10855/async-clipboard-api/
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**Before**
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**After**
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Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3805
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: David Davies-Payne <d2p@me.com>
Co-committed-by: David Davies-Payne <d2p@me.com>
(cherry picked from commit e4c3c039be)