build(deps): bump ajv from 6.11.0 to 6.12.0

Bumps [ajv](https://github.com/epoberezkin/ajv) from 6.11.0 to 6.12.0.
- [Release notes](https://github.com/epoberezkin/ajv/releases)
- [Commits](ajv-validator/ajv@v6.11.0...v6.12.0)

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

package.json

@@ -25,7 +25,7 @@
   "dependencies": {
     "@wmfs/j2119": "1.11.0",
     "@wmfs/statelint": "1.12.0",
-    "ajv": "6.11.0",
+    "ajv": "6.12.0",
     "lodash.clonedeep": "4.5.0",
     "lodash.kebabcase": "4.1.1"
   },