Backport ajv and autocannon updates (#1296)

* Backport ajv and autocannon updates

* Ajv 6.6.1

Author: cemremengu

package.json

@@ -73,7 +73,7 @@
   "devDependencies": {
     "@types/node": "^10.11.0",
     "JSONStream": "^1.3.3",
-    "autocannon": "^3.0.0",
+    "autocannon": "^3.2.0",
     "branch-comparer": "^0.4.0",
     "concurrently": "^4.0.0",
     "cors": "^2.8.4",
@@ -110,7 +110,7 @@
   "dependencies": {
     "@types/pino": "^4.16.0",
     "abstract-logging": "^1.0.0",
-    "ajv": "6.5.5",
+    "ajv": "^6.6.1",
     "avvio": "^5.8.0",
     "end-of-stream": "^1.4.1",
     "fast-json-stringify": "^1.8.0",