fix: showing/hiding was using wrong css 'display' property

Signed-off-by: Jonathan <theflametrooper@gmail.com>

example/index.js

@@ -20,6 +20,7 @@ const TestNotification = new Toast({
 
 const TestNotification3 = new Toast({
 	content: "lorem ispum lorem hello my name is lorem ispum lorem ispum lorem ispum lorem ispum ",
+	persistent: true,
 	interactable: true
 });
 

src/toasters.js

@@ -122,7 +122,7 @@ export default class Toast {
 
 	show() {
 		if (!this.visible) {
-			this.element.style.display = "block";
+			this.element.style.display = "flex";
 			this.visible = true;
 		}
 	}