Fix Medium Severity 'Regular Expression Denial of Service' vulnerability

[jtart]

Snyk is reporting a vulnerability with a medium severity in the 'content-type-parser' package of 'razzle@2.0.3': https://snyk.io/test/github/bbc/simorgh#npm:content-type-parser:20170905

We should fix this.

[sareh]

According to the Snyk site: There is no fix for content-type-parser. The package was renamed from content-type-parser to whatwg-mimetype, which fixes the issue in version 2.0.0..

Here are the dependencies:
razzle@2.0.3 › jest@20.0.4 › jest-cli@20.0.4 › jest-environment-jsdom@20.0.3 › jsdom@9.12.0 › content-type-parser@1.0.2

It appears to be the case that by updating to use jest@23.1.0, this security vulnerability is addressed. New dependency tree would be this:
jest@23.1.0 > jest-cli@23.1.0> jest-environment-jsdom@23.1.0 > jsdom@^11.5.1 which installs jsdom@11.11.0 > whatwg-mimetype@2.1.0.

We can open a PR against Razzle to update the version of Jest being used from "20.0.4" to "^23.1.0" https://github.com/jaredpalmer/razzle/blob/master/packages/razzle/package.json

[jamesbhobbs]

@sareh Sounds good, when you do please add the issue and PR here

[jamesbhobbs]

See jaredpalmer/razzle#438