fix(forget): populate retention groups for manual runs

internal/restic/runner.go

@@ -322,7 +322,7 @@ type ForgetGroup struct {
 // any keep-* would delete every snapshot in the tagged set).
 // Returns the first error encountered, or nil when every group runs
 // to a clean exit.
-func (e Env) RunForget(ctx context.Context, groups []ForgetGroup, handle LineHandler) error {
+func (e Env) RunForget(ctx context.Context, groups []ForgetGroup, dryRun bool, handle LineHandler) error {
 	if len(groups) == 0 {
 		return fmt.Errorf("restic forget: refusing to run with no groups (would be a no-op)")
 	}
@@ -332,6 +332,9 @@ func (e Env) RunForget(ctx context.Context, groups []ForgetGroup, handle LineHan
 		}
 		args := []string{"forget", "--json", "--tag", g.Tag}
 		args = append(args, g.Policy.args()...)
+		if dryRun {
+			args = append(args, "--dry-run")
+		}
 		cmd := e.resticCmd(ctx, args...)
 		if err := runWithPump(cmd, handle); err != nil {
 			return err