v4.8.4

• bumped log4j to 2.15.0 (Please note that so far Membrane Service Proxy used log4j 1.2.17, which was NOT affected by CVE-2021-44228 aka log4shell, and similar attack vectors required very special (let me say: unusual) log4j configurations - or a log4j.properties which could be controlled by the attacker. The bump of log4j is primarily provided to satisfy security guidelines requiring log4j >= 2.15.0.)
• updated environment libraries for automated tests
• improved experimental Kubernetes integration