This helps dedupe dependencies in Sinon. See https://github.com/sinonjs/sinon/issues/2224

As can be seen at https://github.com/nodejs/Release, Node 8 reached "end" of life on 2019-12-31, and is no longer actively supported.

We will stop testing in Node 8 and start testing in Node 13, which will become the next LTS release from April 2020.

• add support for formatting maps
• Update @sinonjs/samsam to version that has isMap method