fix: package.json & .snyk to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/npm:extend:20180424
- https://snyk.io/vuln/npm:hoek:20180212
- https://snyk.io/vuln/npm:tunnel-agent:20170305
- https://snyk.io/vuln/npm:validator:20150313
- https://snyk.io/vuln/npm:validator:20160218


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

.snyk

@@ -0,0 +1,8 @@
+# Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
+version: v1.19.0
+ignore: {}
+# patches apply the minimum changes required to fix a vulnerability
+patch:
+  SNYK-JS-LODASH-567746:
+    - azure-storage > request > form-data > async > lodash:
+        patched: '2021-04-01T15:54:54.459Z'

package.json

@@ -23,7 +23,7 @@
     "ajv": "6.12.2",
     "async": "~2.6.1",
     "aws-sdk": "2.80.0",
-    "azure-storage": "~2.1.0",
+    "azure-storage": "~2.10.2",
     "backo": "^1.1.0",
     "bson": "4.0.0",
     "debug": "~4.1.0",
@@ -45,7 +45,8 @@
     "utf8": "3.0.0",
     "uuid": "^3.0.1",
     "werelogs": "scality/werelogs#0ff7ec82",
-    "xml2js": "~0.4.23"
+    "xml2js": "~0.4.23",
+    "snyk": "^1.521.0"
   },
   "optionalDependencies": {
     "ioctl": "2.0.1"
@@ -71,6 +72,9 @@
     "coverage": "yarn coverage_unit && yarn coverage_ft && yarn coverage_report",
     "coverage_unit": "nyc --silent yarn test",
     "coverage_ft": "nyc --silent --no-clean yarn ft_test",
-    "coverage_report": "nyc report --all --reporter=text-summary --reporter=lcov"
+    "coverage_report": "nyc report --all --reporter=text-summary --reporter=lcov",
-  }
+    "snyk-protect": "snyk protect",
+    "prepublish": "npm run snyk-protect"
+  },
+  "snyk": true
 }