fix: actually respect changelog.abbrev (#4942)

Some changelogers were always returning the short sha instead of the
full one, so setting an abbrev had no effect.

This fixes these changelogers, which should now always return the full
sha.

Note that github usually still shortens the SHAs rendered in markdown,
so the changes might not even be visible in most cases.

closes #4829

internal/client/gitea.go

@@ -84,7 +84,7 @@ func (c *giteaClient) Changelog(_ *context.Context, repo Repo, prev, current str
 
 	for _, commit := range result.Commits {
 		log = append(log, ChangelogItem{
-			SHA:            commit.SHA[:7],
+			SHA:            commit.SHA,
 			Message:        strings.Split(commit.RepoCommit.Message, "\n")[0],
 			AuthorName:     commit.Author.FullName,
 			AuthorEmail:    commit.Author.Email,