fix(diff): don't include signoffs when formatting patch

Diff tests keep failing bacause I have format.signOff set to true in my
gitconfig

Author: aymanbagabas

repo_diff.go

@@ -126,15 +126,15 @@ func (r *Repository) RawDiff(rev string, diffType RawDiffFormat, w io.Writer, op
 		if commit.ParentsCount() == 0 {
 			cmd = cmd.AddArgs("format-patch").
 				AddOptions(opt.CommandOptions).
-				AddArgs("--full-index", "--no-signature", "--stdout", "--root", rev)
+				AddArgs("--full-index", "--no-signoff", "--no-signature", "--stdout", "--root", rev)
 		} else {
 			c, err := commit.Parent(0)
 			if err != nil {
 				return err
 			}
 			cmd = cmd.AddArgs("format-patch").
 				AddOptions(opt.CommandOptions).
-				AddArgs("--full-index", "--no-signature", "--stdout", rev+"..."+c.ID.String())
+				AddArgs("--full-index", "--no-signoff", "--no-signature", "--stdout", rev+"..."+c.ID.String())
 		}
 	default:
 		return fmt.Errorf("invalid diffType: %s", diffType)