Added support for .NET Core 3.0 and AppMetrics 3.2.0

[devtwogenies]

The issue or feature being addressed

• 27

Details on the issue fix or feature implementation

Added support for .NET Core 3.0 and AppMetrics 3.2.0

Confirm the following

• [X] I have ensured that I have merged the latest changes from the dev branch
• [X] I have successfully run a local build
• [X] I have included unit tests for the issue/feature
• [X] I have included the github issue number in my commits

[Davee02]

any chance getting this merged?

[Lonli-Lokli]

Is this project supported?

[ercanerdogan]

Are you going to merge this .netcore 3.0 support?