Updates fixturenet-plugeth stack for the Deneb fork based on Geth v1.13.x:
- updates genesis generator tool, and simplifies the config: the default from `ethereum-genesis-generator` can be used for a from-genesis Merged chain.
Reviewed-on: #789
Reviewed-by: jonathanface <jonathanface@noreply.git.vdb.to>
Reviewed-by: Thomas E Lackey <telackey@noreply.git.vdb.to>
