Upgrade axios to 0.19.0

[nokome]

Over in stencila, npm audit is giving us the following

                       === npm audit security report ===                        

┌──────────────────────────────────────────────────────────────────────────────┐
│                                Manual Review                                 │
│            Some vulnerabilities require your attention to resolve            │
│                                                                              │
│         Visit https://go.npm.me/audit-guide for additional guidance          │
└──────────────────────────────────────────────────────────────────────────────┘
┌───────────────┬──────────────────────────────────────────────────────────────┐
│ Moderate      │ Denial of Service                                            │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ axios                                                        │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Patched in    │ >=0.18.1                                                     │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ @stencila/encoda                                             │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ @stencila/encoda > datapackage > axios                       │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://npmjs.com/advisories/880                             │
└───────────────┴──────────────────────────────────────────────────────────────┘
<snip>

This should resolve that by upgrading axios to 0.19.0.

Note that npm outdated and npm audit show many other packages could also be updated. However, they are mainly dev dependencies so I haven't addressed them since they do not affect us and I didn't want to risk breaking things.

[rufuspollock]

@nokome thanks for this!

@roll can we get this published ?

[roll]

Thanks.

It's released - https://www.npmjs.com/package/datapackage

[nokome]

Thanks for your quick attention to this!