Bump ajv from 6.11.0 to 6.12.6

Bumps [ajv](https://github.com/ajv-validator/ajv) from 6.11.0 to 6.12.6.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](https://github.com/ajv-validator/ajv/compare/v6.11.0...v6.12.6)

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

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

package-lock.json

@@ -1,13 +1,13 @@
 {
   "name": "ushio-mail",
-  "version": "1.0.0",
+  "version": "1.0.3",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
     "ajv": {
-      "version": "6.11.0",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.11.0.tgz",
-      "integrity": "sha512-nCprB/0syFYy9fVYU1ox1l2KN8S9I+tziH8D4zdZuLT3N6RMlGSGt5FSTpAiHB/Whv8Qs1cWHma1aMKZyaHRKA==",
+      "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",