Bump ajv from 5.2.5 to 8.12.0

Bumps [ajv](https://github.com/ajv-validator/ajv) from 5.2.5 to 8.12.0.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v5.2.5...v8.12.0)

---
updated-dependencies:
- dependency-name: ajv
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

package.json

@@ -55,7 +55,7 @@
     "@types/react-addons-test-utils": "0.14.15",
     "@types/react-addons-update": "0.14.14",
     "@types/webpack-env": "~1.15.2",
-    "ajv": "~5.2.2",
+    "ajv": "~8.12.0",
     "amd-loader": "0.0.8",
     "gulp": "4.0.2",
     "husky": "^6.0.0",