Bump @parity/api from 2.1.24 to 5.1.15

Bumps [@parity/api](https://github.com/paritytech/js-libs) from 2.1.24 to 5.1.15.
- [Release notes](https://github.com/paritytech/js-libs/releases)
- [Changelog](https://github.com/paritytech/js-libs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/paritytech/js-libs/commits/v5.1.15)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -171,7 +171,7 @@
     "yauzl": "2.10.0"
   },
   "dependencies": {
-    "@parity/api": "2.1.24",
+    "@parity/api": "5.1.15",
     "@parity/mobx": "1.1.4",
     "@parity/plugin-signer-account": "github:parity-js/plugin-signer-account#05294dce59b7cd7c4f1b26dc604fc6a04dd02bc8",
     "@parity/plugin-signer-default": "github:parity-js/plugin-signer-default#dcf8cf23bb050070b6a691413b974b5c2d7d1ce6",