upgrade libs

* diff
* nodemailer
* sinon
* sinon-chai

package.json

@@ -71,7 +71,7 @@
     "cookie-parser": "^1.4.3",
     "cross-env": "^5.0.5",
     "csrf": "~3.0.3",
-    "diff": "^3.5.0",
+    "diff": "^4.0.1",
     "elasticsearch": "^15.0.0",
     "entities": "^1.1.1",
     "env-cmd": "^8.0.1",
@@ -101,7 +101,7 @@
     "mongoose-paginate": "^5.0.3",
     "mongoose-unique-validator": "^2.0.2",
     "multer": "~1.4.0",
-    "nodemailer": "^4.0.1",
+    "nodemailer": "^5.1.1",
     "nodemailer-ses-transport": "~1.5.0",
     "npm-run-all": "^4.1.2",
     "passport": "^0.4.0",
@@ -196,8 +196,8 @@
     "reveal.js": "^3.5.0",
     "sass-loader": "^7.1.0",
     "simple-load-script": "^1.0.2",
-    "sinon": "^7.0.0",
-    "sinon-chai": "^3.2.0",
+    "sinon": "^7.2.2",
+    "sinon-chai": "^3.3.0",
     "socket.io-client": "^2.0.3",
     "stream-to-promise": "^2.2.0",
     "style-loader": "^0.23.0",