Bump NuGet.Packaging to 7.9.0 to match the SDK's NuGet version - #639

NuGet.Protocol.Core.Types.FatalProtocolException : An error occurred while retrieving package metadata for 'Microsoft.NETCore.App.Ref.3.1.0' from source 'nuget.org'. ---- System.MethodAccessException : Attempt by method 'NuGet.Protocol.ResolverMetadataClient+<GetRegistrationInfo>d__2.MoveNext()' to access method 'NuGet.Frameworks.NuGetFrameworkFullComparer..ctor()' failed.

NuGet.Protocol.Core.Types.FatalProtocolException : An error occurred while retrieving package metadata for 'Microsoft.NETCore.App.Ref.3.1.0' from source 'nuget.org'. ---- System.MethodAccessException : Attempt by method 'NuGet.Protocol.ResolverMetadataClient+<GetRegistrationInfo>d__2.MoveNext()' to access method 'NuGet.Frameworks.NuGetFrameworkFullComparer..ctor()' failed.

[xUnit.net 00:00:01.43] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.FlagsBareNukeBuildBaseType [FAIL]

[xUnit.net 00:00:01.43] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.FlagsUsingNamespaceDirective [FAIL]

[xUnit.net 00:00:01.42] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.FlagsUsingStaticDirective [FAIL]

[xUnit.net 00:00:01.42] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.DoesNotFireOnUnrelatedIdentifiers [FAIL]

[xUnit.net 00:00:01.42] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.FlagsBareINukeBuildBaseInterface [FAIL]

[xUnit.net 00:00:01.41] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.FlagsFullyQualifiedTypeReference [FAIL]

[xUnit.net 00:00:01.41] Fallout.Migrate.Analyzers.Specs.NukeMigrationAnalyzerSpecs.DoesNotFireWhenProjectDoesNotReferenceFallout [FAIL]

[xUnit.net 00:00:00.49] Fallout.Migrate.Analyzers.Specs.RealWorldSmokeSpecs.RewritesRealisticPreRenameBuildClass [FAIL]

'HelmLintSettings.Set' hides inherited member 'Options.Set(string, object)'. Use the new keyword if hiding was intended.

'HelmInstallSettings.Set' hides inherited member 'Options.Set(string, object)'. Use the new keyword if hiding was intended.

'DockerBuildxCreateSettings.Config' hides inherited member 'DockerOptionsBase.Config'. Use the new keyword if hiding was intended.

'DockerConfigCreateSettings.Config' hides inherited member 'DockerOptionsBase.Config'. Use the new keyword if hiding was intended.

'DockerServiceCreateSettings.Config' hides inherited member 'DockerOptionsBase.Config'. Use the new keyword if hiding was intended.

XML comment has badly formed XML -- 'Expected an end tag for element 'summary'.'

XML comment has badly formed XML -- 'Expected an end tag for element 'var'.'

XML comment has badly formed XML -- 'Expected an end tag for element 'type'.'

XML comment has badly formed XML -- 'End tag 'summary' does not match the start tag 'value'.'