Drop support for node 8 / 9

[epicfaace]

Reasons for making this change

Node 8 / 9 are no longer supported, and some of our dependencies no longer support these versions at all (see #2030, #2014).

[jimmycallin]

💯 💯

But I think you also need to update the engines key value in the various package.json, and whatever it is that sets the required builds in the CI check.

[stanlemon]

Awesome! One thought, doesn't 10 end the maintenance window in April?

[epicfaace]

That's true, though I think we can wait a bit before actually dropping support for it.

[stanlemon]

That's true, though I think we can wait a bit before actually dropping support for it.

Sure, I was just thinking in terms of v3 and breaking changes is all.

[epicfaace]

Yeah, that's a good point. I guess we might as well drop official support for it (though it will likely still work on Node 10, we can just remove it from CI).

[epicfaace]

Please take a look: #2299