fix: serverless/package.json & serverless/.snyk to reduce vulnerabilities

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

Author: snyk-bot

serverless/.snyk

@@ -0,0 +1,8 @@
+# Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
+version: v1.14.1
+ignore: {}
+# patches apply the minimum changes required to fix a vulnerability
+patch:
+  SNYK-JS-LODASH-567746:
+    - firebase-functions > lodash:
+        patched: '2020-05-03T04:51:30.350Z'