[Interactive Graph: Circle] Add a key prop to the circle drag handle (#…

…1388)

## Summary:
There's always a console error saying that the circle graph drag handle
is missing the `key` prop.

Adding a `key` here.

Issue: none

## Test plan:
Open the console and make sure the error isn't showing up anymore.

`yarn jest packages/perseus/src/widgets/__tests__/interactive-graph.test.ts`
Make sure the logs don't show the console error anymore.

<img width="494" alt="Screenshot 2024-07-01 at 3 10 31 PM" src="https://github.com/Khan/perseus/assets/13231763/2e3cd2cd-7c08-4527-9fcb-aa02b096189f">

Author: nishasy

Reviewers: benchristel, catandthemachines

Required Reviewers:

Approved By: benchristel, catandthemachines

Checks: ✅ codecov/project, ✅ codecov/patch, ✅ Upload Coverage (ubuntu-latest, 20.x), ✅ Publish npm snapshot (ubuntu-latest, 20.x), ✅ Cypress (ubuntu-latest, 20.x), ✅ Jest Coverage (ubuntu-latest, 20.x), ✅ Check builds for changes in size (ubuntu-latest, 20.x), ✅ Lint, Typecheck, Format, and Test (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x), 🚫 Upload Coverage, ✅ gerald, 🚫 Publish npm snapshot (ubuntu-latest, 20.x), 🚫 Lint, Typecheck, Format, and Test (ubuntu-latest, 20.x), 🚫 Cypress (ubuntu-latest, 20.x), 🚫 Check for .changeset entries for all changed files (ubuntu-latest, 20.x), 🚫 Jest Coverage (ubuntu-latest, 20.x), ✅ Publish Storybook to Chromatic (ubuntu-latest, 20.x), 🚫 Check builds for changes in size (ubuntu-latest, 20.x), ✅ gerald

Pull Request URL: #1388

.changeset/sour-cougars-draw.md

@@ -0,0 +1,5 @@
+---
+"@khanacademy/perseus": patch
+---
+
+[Interactive Graph: Circle] Add a key prop to the circle drag handle

packages/perseus/src/widgets/interactive-graphs/graphs/circle.tsx

@@ -108,6 +108,7 @@ function DragHandle(props: {center: [x: number, y: number]}) {
                 const [xPx, yPx] = vec.add(offsetPx, centerPx);
                 return (
                     <circle
+                        key={`circle-${xPx}-${yPx}`}
                         className="movable-circle-handle-dot"
                         cx={xPx}
                         cy={yPx}