Bump ajv from 6.12.2 to 6.12.6

Bumps [ajv](https://github.com/ajv-validator/ajv) from 6.12.2 to 6.12.6.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](https://github.com/ajv-validator/ajv/compare/v6.12.2...v6.12.6)

---
updated-dependencies:
- dependency-name: ajv
  dependency-type: indirect
...

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

package-lock.json

@@ -2479,9 +2479,9 @@
       }
     },
     "ajv": {
-      "version": "6.12.3",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.3.tgz",
-      "integrity": "sha512-4K0cK3L1hsqk9xIb2z9vs/XU+PGJZ9PNpJRDS9YLzmNdX6jmVPfamLvTJr0aDAusnHyCHO6MjzlkAsgtqp9teA==",
+      "version": "6.12.6",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
+      "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
       "requires": {
         "fast-deep-equal": "^3.1.1",
         "fast-json-stable-stringify": "^2.0.0",