Building with .Net Framework 4.5.2

[Netizine]

Describe the bug

.Net framework 4.5.2 has gone end of life. https://dotnet.microsoft.com/en-us/download/dotnet-framework/net452

Expected behavior:

Upgrade to 4.6.2 which has support

[StefH]

Good point. However for now I'll keep the backwards versions. (Also .NET 5.0 is out of supported, and also netcore2.1)