The framework 'Microsoft.NETCore.App', version '2.1.0' was not found

[vijayganeshpk]

Describe the bug]
Unable to run out of process migration on MacOS Catalina

When trying to run dotnet-fm getting error

It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '2.1.0' was not found.
  - The following frameworks were found:
      3.1.6 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

You can resolve the problem by installing the specified framework and/or SDK.

The specified framework can be found at:
  - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=2.1.0&arch=x64&rid=osx.10.15-x64

To Reproduce

1. Install global tool dotnet tool install -g FluentMigrator.DotNet.Cli
2. Try to execute the tool even without any parameters dotnet-fm

Expected behavior
Get an help text

Information (please complete the following information):

• OS: MacOS Catalina 10.15.6
• Platform [.NET Framework 4.x / .NET Core 2.x , etc]: .NET Core 3.1.302
• FluentMigrator version [ e.g 3.2.1 ]: 3.2.8
• FluentMigrator runner [ FluentMigrator.MSBuild, FluentMigrator.Console, FluentMigrator.DotNet.Cli, or "in-process runner" ]: FluentMigrator.DotNet.Cli
• Database Management System [ SQLServer, SQLite, Mysql, Postgres, Firebird, Oracle, Redshift, DB2, DB2 ISeries, SAP Hana, SAP SQL Anywhere ]: Postgres
• Database Management System Version [ e.g., "SQL Server 2019 Enterprise Edition", "Oracle 18xe", etc ]

Additional context
I am not even getting the initial help text message from dotnet-fm

[jzabroski]

Hi @vijayganeshpk Thanks for reporting this. Unfortunately, this is not a bug - it is exactly what the message indicates. When you run dotnet-fm, what you are actually running is dotnet.exe, so the error message you get is before dotnet-fm even executes.

The solution for now is to install .NET Core 2.1. We're working on #1178