Require Node 12 (at least 10)

[consideRatio]

We specify that node >=6 is required, but in practice we test only against 10+ where tests are flaky on node 10.

Node 10 is no longer actively maintained, only node 12+ is under active maintenance at the moment. I suggest we bump our requirement from node >= 6 to node >= 12.

@minrk and @manics what do you think? I believe our outdated specification of this relates to several issues we have run into in the past about TLS matters and now more recently perhaps also #321. Do you agree to require node >= 12?

configurable-http-proxy/package.json

Lines 26 to 28 in 790a8c7

	"engines": {
	"node": ">= 6.0"
	},

[consideRatio]

This did in fact solve another issue, i'll open a PR unless someone beats me to it (currently on mobile)!