fix(deps): bump ajv from 6.10.2 to 6.12.3

Bumps [ajv](https://github.com/ajv-validator/ajv) from 6.10.2 to 6.12.3.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v6.10.2...v6.12.3)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -35,7 +35,7 @@
     ]
   },
   "dependencies": {
-    "ajv": "6.10.2",
+    "ajv": "6.12.3",
     "caseless": "0.12.0",
     "clone": "2.1.2",
     "commander": "3.0.2",