Compatibility issue: lambda-event-mock@1.5.0 requires node>=12.13

[RomainMuller]

Hey,

Since lambda-tester claims to support node 10.x and 12.x, it should not take a dependency on lambda-event-mock@1.5.0 as this requires node >= 12.13: https://github.com/vandium-io/lambda-event-mock/blob/901aadcd6fcfd51649408dfe008b1ccfebf178fe/package.json#L20

This actually breaks installs done using yarn on a node platform at 10.x because of the engine incompatibility issue.

Alternatively, you might want to stop advertising support for node 10.x on the 4.x branch.

Regards,
Romain.