[bugfix] prevent clicking Enter in description field from deleting the image (#4436)

# Description

Change the type of "Delete header" / "Delete avatar" button to just "button" to prevent them from getting deleted if user presses Enter in the description field.

Closes https://codeberg.org/superseriousbusiness/gotosocial/issues/4363

## Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: `[ ]` -> `[x]`

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [ ] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [ ] I/we have commented the added code, particularly in hard-to-understand areas.
- [x] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [ ] I/we have run tests and they pass locally with the changes.
- [x] I/we have run `go fmt ./...` and `golangci-lint run`.

Co-authored-by: ptrcnull <git@ptrcnull.me>
Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4436
Co-authored-by: ptrcnull <ptrcnull@noreply.codeberg.org>
Co-committed-by: ptrcnull <ptrcnull@noreply.codeberg.org>

0 files changed, 0 insertions, 0 deletions