Bump validator from 11.0.0 to 13.7.0 in /back-end

Bumps [validator](https://github.com/validatorjs/validator.js) from 11.0.0 to 13.7.0.
- [Release notes](https://github.com/validatorjs/validator.js/releases)
- [Changelog](https://github.com/validatorjs/validator.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/validatorjs/validator.js/compare/11.0.0...13.7.0)

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

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

back-end/package.json

@@ -23,7 +23,7 @@
     "mongoose": "5.7.5",
     "nodemailer": "6.3.0",
     "nodemon": "1.19.1",
-    "validator": "11.0.0",
+    "validator": "13.7.0",
     "web3": "^1.0.0-beta.55",
     "web3-utils": "^1.0.0-beta.55",
     "winston": "3.2.1",

back-end/yarn.lock

@@ -3506,7 +3506,7 @@ minimist@0.0.8:
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.8.tgz#857fcabfc3397d2625b8228262e86aa7a011b05d"
   integrity sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=
 
-minimist@^1.2.0, minimist@^1.2.2:
+minimist@^1.2.0:
   version "1.2.2"
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-1.2.2.tgz#b00a00230a1108c48c169e69a291aafda3aacd63"
   integrity sha512-rIqbOrKb8GJmx/5bc2M0QchhUouMXSpd1RTclXsB41JdL+VtnojfaJR+h7F9k18/4kHUsBFgk80Uk+q569vjPA==
@@ -5677,10 +5677,10 @@ validate-npm-package-license@^3.0.1:
     spdx-correct "^3.0.0"
     spdx-expression-parse "^3.0.0"
 
-validator@11.0.0:
-  version "11.0.0"
-  resolved "https://registry.yarnpkg.com/validator/-/validator-11.0.0.tgz#fb10128bfb1fd14ce4ed36b79fc94289eae70667"
-  integrity sha512-+wnGLYqaKV2++nUv60uGzUJyJQwYVOin6pn1tgEiFCeCQO60yeu3Og9/yPccbBX574kxIcEJicogkzx6s6eyag==
+validator@13.7.0:
+  version "13.7.0"
+  resolved "https://registry.yarnpkg.com/validator/-/validator-13.7.0.tgz#4f9658ba13ba8f3d82ee881d3516489ea85c0857"
+  integrity sha512-nYXQLCBkpJ8X6ltALua9dRrZDHVYxjJ1wgskNt1lH9fzGjs3tgojGSCBjmEPwkWS1y29+DrizMTW19Pr9uB2nw==
 
 value-or-function@^3.0.0:
   version "3.0.0"