add default reqTimeout

[AndreMaz]

Fixes https://github.com/moleculerjs/moleculer-web/issues/206

In node.js versions < v18 this was set to 0 (meaning disabled).

However, in the docs it is stated that:

It must be set to a non-zero value (e.g. 120 seconds) to protect against potential Denial-of-Service attacks in case the server is deployed without a reverse proxy in front.

In node.js v18 the default value is 300000 ms = 5 minutes,

This PR uses node.js v18 default value

[intech]

@AndreMaz Thanks so much!