Remove .NET Frameworks older than net462

[cijothomas]

Similar to and continuing from : #2138

1.2.0 already removed net452 and net46. This issue is tracking the removal of net461.
https://devblogs.microsoft.com/dotnet/net-framework-4-5-2-4-6-4-6-1-will-reach-end-of-support-on-april-26-2022/

[cijothomas]

Closing as this is completed.