make sure `gh` binary exists

[6543]

https://github.com/go-gitea/gitea/actions/runs/6864716362/job/18667116788 :

Run gh release create v1.21.0 --title v1.21.0 --draft --notes-from-tag dist/release/*
/home/runner/work/_temp/df1f597e-b671-4a36-8c9b-df8014b8f9a3.sh: line 1: gh: command not found
Error: Process completed with exit code 127.

affects v1.20.x and main

gitea/.github/workflows/release-tag-version.yml

Lines 61 to 65 in f65977d

	- name: create github release
	run: |
	gh release create ${{ github.ref_name }} --title ${{ github.ref_name }} --draft --notes-from-tag dist/release/*
	env:
	GITHUB_TOKEN: ${{ secrets.RELEASE_TOKEN }}

also we should make sure gh release dont fail if release was already created and overwrite artifacts (as it was done with drone plugin)