Bump ajv from 5.5.2 to 6.12.3

Bumps [ajv](https://github.com/ajv-validator/ajv) from 5.5.2 to 6.12.3.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v5.5.2...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

@@ -32,7 +32,7 @@
     "@angular/router": "^8.2.14",
     "@types/jquery": "^3.3.29",
     "@types/lodash": "^4.14.109",
-    "ajv": "^5.5.2",
+    "ajv": "^6.12.3",
     "algebra.js": "^0.2.6",
     "algotrader": "^1.3.1",
     "angular-highcharts": "^9.0.11",