fix: Bump node-fetch dep to pick up security release

[max-stytch]

Force bumps node-fetch to 2.6.7 to resolve https://nvd.nist.gov/vuln/detail/CVE-2022-0235

stytch@5.4.0 /Users/maxwellgerber/work/client-libs/stytch-node
└─┬ isomorphic-unfetch@3.1.0
  └── node-fetch@2.6.7

[jeremy-stytch]

I haven't dug too deep into the issue, but "Up to (excluding) 3.1.1" makes me think we should also bump our direct dependency. But I may just be misunderstanding the override system with multiple versions of the same dependency around.

Suggested change

	"isomorphic-unfetch": "^3.1.0",
	"isomorphic-unfetch": "^3.1.1",

[max-stytch]

I took a look into node-fetch and the reported issue isn't fixed in the latest - opened node-fetch/node-fetch#1599