chore(deps): update dependency @types/node to 14.x

[alexrudd2]

The @types/node package got out of sync with the tested versions of node.

Versions higher than 14 trigger type errors in express-server-static-core. (They have no practical runtime effect, but break tsc)

Error: node_modules/@types/express-serve-static-core/index.d.ts(471,18): 
error TS2430: Interface 'Response' incorrectly extends interface 
'ServerResponse<IncomingMessage>'.
  Property 'req' is optional in type 'Response' but required in type 
'ServerResponse<IncomingMessage>'.
Error: src/server.ts(18,11): error TS2769: No overload matches this call.
  The last overload gave the following error.
    Argument of type 'NextHandleFunction' is not assignable to parameter 
of type 'PathParams'.

I know you typically don't like package-lock.json updates but this one is so short I left it in.