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-HTTPSPROXYAGENT-469131

.snyk

@@ -0,0 +1,20 @@
+# Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
+version: v1.13.5
+ignore: {}
+# patches apply the minimum changes required to fix a vulnerability
+patch:
+  SNYK-JS-HTTPSPROXYAGENT-469131:
+    - googleapis > google-auth-library > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'
+    - googleapis > googleapis-common > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'
+    - googleapis > google-auth-library > gcp-metadata > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'
+    - googleapis > google-auth-library > gtoken > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'
+    - googleapis > googleapis-common > google-auth-library > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'
+    - googleapis > googleapis-common > google-auth-library > gcp-metadata > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'
+    - googleapis > googleapis-common > google-auth-library > gtoken > gaxios > https-proxy-agent:
+        patched: '2019-10-04T02:36:00.628Z'