Bump ajv from 6.7.0 to 6.12.3

Bumps [ajv](https://github.com/ajv-validator/ajv) from 6.7.0 to 6.12.3.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v6.7.0...v6.12.3)

---
updated-dependencies:
- dependency-name: ajv
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package-lock.json

@@ -20,7 +20,7 @@
     "vue": "^2.5.22"
   },
   "dependencies": {
-    "ajv": "^6.7.0",
+    "ajv": "^6.12.3",
     "bootstrap": ">=4.1.2",
     "hoek": "^4.2.1",
     "popper.js": "^1.14.6",