chore:(deps): bump @testing-library/user-event in /explorer (#15509)

Bumps [@testing-library/user-event](https://github.com/testing-library/user-event) from 12.7.2 to 12.7.3.
- [Release notes](https://github.com/testing-library/user-event/releases)
- [Changelog](https://github.com/testing-library/user-event/blob/master/CHANGELOG.md)
- [Commits](testing-library/user-event@v12.7.2...v12.7.3)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

explorer/package.json

@@ -9,7 +9,7 @@
     "@solana/web3.js": "^0.92.2",
     "@testing-library/jest-dom": "^5.11.9",
     "@testing-library/react": "^11.2.5",
-    "@testing-library/user-event": "^12.7.2",
+    "@testing-library/user-event": "^12.7.3",
     "@types/bn.js": "^5.1.0",
     "@types/bs58": "^4.0.1",
     "@types/chai": "^4.2.15",