Fix avatar template error (#13833)

Fixes: https://github.com/go-gitea/gitea/issues/13831

templates/repo/shabox_badge.tmpl

@@ -3,7 +3,7 @@
 		<div title="{{if eq .verification.TrustStatus "trusted"}}{{else if eq .verification.TrustStatus "untrusted"}}{{$.root.i18n.Tr "repo.commits.signed_by_untrusted_user"}}: {{else}}{{$.root.i18n.Tr "repo.commits.signed_by_untrusted_user_unmatched"}}: {{end}}{{.verification.Reason}}">
 		{{if ne .verification.SigningUser.ID 0}}
 			{{svg "gitea-lock"}}
-			{{avatar .verification.SigningUser "signature"}}
+			{{avatar .verification.SigningUser 28 "signature"}}
 		{{else}}
 			<span title="{{$.root.i18n.Tr "gpg.default_key"}}">{{svg "gitea-lock-cog"}}</span>
 			{{avatarByEmail .verification.SigningEmail "" 28 "signature"}}