[VideoThumbnail] Fix validateDOMNesting warning (#7911)

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### WHY are these changes introduced?
There are two pretty loud `validateDOMNesting` warnings logged in
development that seem to be originating from the `VideoThumbnail`
component:
<img width="712" alt="Screenshot 2022-12-13 at 5 14 02 PM"
src="https://user-images.githubusercontent.com/9685204/207456198-d3b2a437-869a-4f9e-9441-44bbb851839e.png">

<!--
  Context about the problem that’s being addressed.
-->

### WHAT is this pull request doing?
I'm hoping that this extremely naive fix might just do the trick, but I
have not tested this beyond storybook. If there are any considerations
that I missed, please let me know.

Visually, there does not appear to be a difference after the `p` is
changed to a `div`

**Before**:
<img width="737" alt="Screenshot 2022-12-13 at 5 15 53 PM"
src="https://user-images.githubusercontent.com/9685204/207456176-e05c764b-ff91-4d1b-9ad6-e119f9712de4.png">

**After**:
<img width="737" alt="Screenshot 2022-12-13 at 5 15 40 PM"
src="https://user-images.githubusercontent.com/9685204/207456189-bcb7913b-befd-46b9-999f-c23ee023295b.png">

<!-- ℹ️ Delete the following for small / trivial changes -->

### How to 🎩

🖥 [Local development
instructions](https://github.com/Shopify/polaris/blob/main/README.md#local-development)
🗒 [General tophatting
guidelines](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md)
📄 [Changelog
guidelines](https://github.com/Shopify/polaris/blob/main/.github/CONTRIBUTING.md#changelog)

I added the snapshot to a Notebooks [spin
instance](https://admin.web.video-thumbnail-fix.ben-milton.us.spin.dev/store/shop1/apps/development-notebooks-key/),
where we have a `VideoThumbnail` component on the main index page.
1. Ensure that the `validateDOMNesting` warnings are now gone from the
dev console
2. Ensure that the `VideoThumbnail` and timestamp in particular still
works and appears the same as before the change

### 🎩 checklist

- [ ] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [ ] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [ ] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [ ] Updated the component's `README.md` with documentation changes
- [ ] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide

Author: bencmilton

.changeset/rude-crabs-jog.md

@@ -0,0 +1,5 @@
+---
+'@shopify/polaris': patch
+---
+
+Fix validateDOMNesting warning in `VideoThumbnail`

polaris-react/src/components/VideoThumbnail/VideoThumbnail.tsx

@@ -77,7 +77,7 @@ export function VideoThumbnail({
   }
 
   const timeStampMarkup = videoLength ? (
-    <p className={styles.Timestamp}>
+    <div className={styles.Timestamp}>
       <Stack alignment="center" spacing="extraTight">
         <span className={styles.PlayIcon}>
           <Icon source={PlayMinor} />
@@ -90,7 +90,7 @@ export function VideoThumbnail({
           {secondsToTimestamp(videoLength)}
         </Text>
       </Stack>
-    </p>
+    </div>
   ) : null;
 
   let progressMarkup = null;