Added an important checkbox

Wanted to add it at the bottom at first, but then thought about potential time waste for those who file an issue and it ends up being a duplicate

.github/ISSUE_TEMPLATE/bug.yml

@@ -3,6 +3,12 @@ description: File a bug report!
 # title: "(Bug): "
 labels: ["bug"]
 body:
+  - type: checkboxes
+    attributes:
+      label: Have you tried to find similar open issues?
+      options:
+        - label: "Yes, this issue is not a duplicate"
+          required: true
   - type: input
     attributes:
       label: Browser