fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/npm:hoek:20180212

Latest report for danielv123/factorioclusterio:
https://snyk.io/test/github/danielv123/factorioclusterio

package.json

@@ -23,7 +23,7 @@
     "averaged-timeseries": "^1.4.0",
     "bcryptjs": "^2.4.3",
     "body-parser": "^1.18.2",
-    "codecov": "^2.3.1",
+    "codecov": "^3.0.1",
     "deepmerge": "^1.5.2",
     "ejs": "^2.5.7",
     "express": "^4.16.2",