v2.1.0

Release notes

• Update powsybl-core to v4.1.0 (#231)
• Draw lines (branches) within a substation (#207)
  
• Creation of a BranchStatus extension (#225)
• Remove viewer app, moved to powsybl-dev-tool (#226)
• Graph classes are non final classes (#228)
• Update github actions to latest versions (#229)
• gephi exclusions gathered in the root pom.xml (#230)
• Remove guava direct dependency (#233)