Update readme

Removed GetError call, deprecated. Protobuf interface to be updated w…

…ith next engine minor version change

feat: update to SheepRLv0.4.8

Update dep in setup.py

fix: dependencies

Add render_mode attribute to gym class, add optional splash screen, f…

…ix make env for custom env_address

Fix random integration test

Update Readme

Specify limit upper limit for diambra-engine version in v.2.1

Prefix version tag with v