fix: upgrade fastify from 2.12.0 to 2.12.1

Snyk has created this PR to upgrade fastify from 2.12.0 to 2.12.1.

See this package in NPM:
https://www.npmjs.com/package/fastify

See this project in Snyk:
https://app.snyk.io/org/mikaelvesavuori/project/d0b2579a-c78c-4130-9920-66edd725bc4b?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

src/package-lock.json

@@ -18,7 +18,7 @@
   "author": "Mikael Vesavuori",
   "license": "ISC",
   "dependencies": {
-    "fastify": "^2.12.0"
+    "fastify": "^2.12.1"
   },
   "devDependencies": {
     "jest": "^25.1.0"