Remove some erroneous apostrophes in comments

include/sway/tree/container.h

@@ -364,7 +364,7 @@ bool container_is_sticky_or_child(struct sway_container *con);
  * This will destroy pairs of redundant H/V splits
  * e.g. H[V[H[app app]] app] -> H[app app app]
  * The middle "V[H[" are eliminated by a call to container_squash
- * on the V[ con. It's grandchildren are added to it's parent.
+ * on the V[ con. It's grandchildren are added to its parent.
  *
  * This function is roughly equivalent to i3's tree_flatten here:
  * https://github.com/i3/i3/blob/1f0c628cde40cf87371481041b7197344e0417c6/src/tree.c#L651

sway/input/seat.c

@@ -245,7 +245,7 @@ static void handle_seat_node_destroy(struct wl_listener *listener, void *data) {
 		seat_node_destroy(seat_node);
 		// If an unmanaged or layer surface is focused when an output gets
 		// disabled and an empty workspace on the output was focused by the
-		// seat, the seat needs to refocus it's focus inactive to update the
+		// seat, the seat needs to refocus its focus inactive to update the
 		// value of seat->workspace.
 		if (seat->workspace == node->sway_workspace) {
 			struct sway_node *node = seat_get_focus_inactive(seat, &root->node);

sway/input/seatop_default.c

@@ -474,7 +474,7 @@ static void handle_button(struct sway_seat *seat, uint32_t time_msec,
 			seat_set_focus(seat, node);
 		}
 
-		// If moving a container by it's title bar, use a threshold for the drag
+		// If moving a container by its title bar, use a threshold for the drag
 		if (!mod_pressed && config->tiling_drag_threshold > 0) {
 			seatop_begin_move_tiling_threshold(seat, cont);
 		} else {