[CSharp] cannot parse open telemetry demo ValkeyCartStore.cs

[talwgx]

The CSharp grammar fails to parse:

https://github.com/open-telemetry/opentelemetry-demo/blob/main/src/cartservice/src/cartstore/ValkeyCartStore.cs

This is due to lines 11 and 22 using newer language constructs (namespace and new(); ). Even though the grammar states it only supports C# up to v6.0 it'll be great if those constructs are supported or even ignored as otherwise parsing of the entire file fails.