[#1598] golangci: Enable unconvert linters

To drop unnecessary conversions.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/morph/event/netmap/epoch.go

@@ -41,7 +41,7 @@ func ParseNewEpoch(e *state.ContainedNotificationEvent) (event.Event, error) {
 	}
 
 	return NewEpoch{
-		Num:  uint64(nee.Epoch.Uint64()),
+		Num:  nee.Epoch.Uint64(),
 		Hash: e.Container,
 	}, nil
 }