KSP updates of its Unity version adds support for net45. This should allow us to build the DLLs for the server and services with net45, and use an official net45 protobuf build (rather than the custom net35 one we use currently).

May also allow us to remove some old net35 workarounds from the code, such as the Tuple implementation in server/src/Utils/Tuple.cs

This should work with KSP 1.8+ as net45 was added (as production ready) in Unity 2018.1.
KSP 1.8+ uses Unity 2019.2.2f1 and KSP 1.12+ uses Unity 2019.4.18f1