fix: package.json & yarn.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-LODASH-1018905
- https://snyk.io/vuln/SNYK-JS-LODASH-1040724

package.json

@@ -39,7 +39,7 @@
     "js-yaml": "^3.7.0",
     "jsonschema": "^1.1.1",
     "jsonwebtoken": "^7.2.1",
-    "lodash": "^4.17.4",
+    "lodash": "^4.17.21",
     "lodash.template": "^4.4.0",
     "method-override": "^2.3.7",
     "nodemailer": "^2.7.0",

yarn.lock

@@ -3106,10 +3106,15 @@ lodash@^3.10.1:
   version "3.10.1"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-3.10.1.tgz#5bf45e8e49ba4189e17d482789dfd15bd140b7b6"
 
-lodash@^4.0.0, lodash@^4.14.0, lodash@^4.17.4, lodash@^4.2.0, lodash@^4.3.0:
+lodash@^4.0.0, lodash@^4.14.0, lodash@^4.2.0, lodash@^4.3.0:
   version "4.17.4"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.4.tgz#78203a4d1c328ae1d86dca6460e369b57f4055ae"
 
+lodash@^4.17.21:
+  version "4.17.21"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"
+  integrity sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==
+
 lodash@~4.16.4:
   version "4.16.6"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.16.6.tgz#d22c9ac660288f3843e16ba7d2b5d06cca27d777"