fix: package.json, package-lock.json & .snyk to reduce vulnerabilities

The following vulnerabilities are fixed with a Snyk patch:
- https://snyk.io/vuln/SNYK-JS-LODASH-567746

.snyk

@@ -0,0 +1,12 @@
+# Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
+version: v1.21.5
+ignore: {}
+# patches apply the minimum changes required to fix a vulnerability
+patch:
+  SNYK-JS-LODASH-567746:
+    - node-sass > lodash:
+        patched: '2021-09-10T09:11:19.781Z'
+    - node-sass > sass-graph > lodash:
+        patched: '2021-09-10T09:11:19.781Z'
+    - node-sass > gaze > globule > lodash:
+        patched: '2021-09-10T09:11:19.781Z'

package.json

@@ -9,7 +9,9 @@
   },
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
-    "build": "gulp minify"
+    "build": "gulp minify",
+    "prepare": "npm run snyk-protect",
+    "snyk-protect": "snyk-protect"
   },
   "publishConfig": {
     "registry": "https://registry.npmjs.org"
@@ -63,6 +65,8 @@
     "Opera >= 30"
   ],
   "dependencies": {
-    "node-sass": "^6.0.1"
-  }
+    "node-sass": "^6.0.1",
+    "@snyk/protect": "latest"
+  },
+  "snyk": true
 }