Remove Unsupported Versions of Node.js from .travis.yml

[nelsonic]

At present we have four versions of Node.js in our .travis.yml file and each one is tested by Travis CI on each commit:

hapi-auth-jwt2/.travis.yml

Lines 1 to 6 in 490f2fe

	language: node_js
	node_js:
	- "8"
	- "10"
	- "11"
	- "node"

Given that both Node version 8 and 11 are no longer supported/maintained, I feel we should remove them.
see: https://nodejs.org/en/about/releases

Does anyone have any objection to the removal of these older versions of Node from .travis.yml?

[nelsonic]

According to this issue hapijs/hapi#4012, the BDFL of Hapi has decided to "Drop node 10"
because "I want to use node v12 features" ...

So even though Node.js v10 is still maintained by the OpenJS Foundation / Node.js Community,
Version 19 of Hapi.js has introduced breaking changes so everyone is forced to upgrade.
This is not a "bad" thing because v12 does introduce numerous performance improvements including a new version of V8. So there does not appear to be any downside to upgrading. It's just a hassle some people weren't expecting, but hopefully not one that will take more than a few minutes of DevOps. 💭

See:

• https://nodejs.org/tr/blog/uncategorized/10-lts-to-12-lts/
• https://blog.risingstack.com/node-js-12-new-features/
• https://jaxenter.com/node-js-12-highlights-158102.html

What does that mean for us?

It means we need to release a new major version if we update our devDependency to Hapi v19.

[nelsonic]

Given that Hapi 19 no longer supports Nod.js version 10.
I'm thinking of adding a line to the Compatibility section of the README.md:

e.g:
hapi-auth-jwt2 version 9.x.x is compatible with Hapi.js 19.x.x which only supports Node.js 12+.
While hapi-auth-jwt2 version 9.0.0 does not have any code changes from v8.8.1 (so there should not be any need to update your code that uses this plugin), we felt it was prudent to make it clear to people that Hapi.js (the core framework) has dropped support for Node.js 10 and they should treat this package as a no longer supporting older versions of Node.

[nelsonic]

Unsupported versions of Node.js removed and note about compatibility added #337 ✅