Update dependency Microsoft.Extensions.Configuration to 5.0.0

[BruceHaley]

Fixes #5751

Description

This updates Microsoft.Extensions.Configuration from version 2.1.0 to 5.0.0 for TargetFramework netcoreapp3.1.
For netcoreapp2.1, version 2.1.0 must be kept because later versions are not compatible.

This must wait until netcoreapp2.1 is dropped. That must wait for v5.0.

Specific Changes

Testing

[coveralls]

Pull Request Test Coverage Report for Build 265143

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.01%) to 75.769%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetPreviousViableTime.cs	1	90.91%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetNextViableTime.cs	2	90.91%

Totals
Change from base Build 264914:	-0.01%
Covered Lines:	23136
Relevant Lines:	30535

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💛 - Coveralls