Bump fastify from 2.15.2 to 3.1.1

Bumps [fastify](https://github.com/fastify/fastify) from 2.15.2 to 3.1.1.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](fastify/fastify@v2.15.2...v3.1.1)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -23,7 +23,7 @@
   },
   "devDependencies": {
     "ava": "^3.0.0",
-    "fastify": "^2.3.0",
+    "fastify": "^3.1.1",
     "nyc": "^15.0.0",
     "request": "^2.88.0",
     "standard": "^14.0.0",