Adding the new .NET Core 3.1 test project to the test project solution

Author: daveaglick

tests/projects/TestProjects.sln

@@ -1,6 +1,6 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 15
-VisualStudioVersion = 15.0.27130.2027
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.30104.148
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LegacyFrameworkProject", "LegacyFrameworkProject\LegacyFrameworkProject.csproj", "{36ED2B9D-2FC2-4725-9BC2-53CABF113477}"
 EndProject
@@ -30,6 +30,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SdkNetCoreProjectWithRefere
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SdkNetStandardProjectWithConstants", "SdkNetStandardProjectWithConstants\SdkNetStandardProjectWithConstants.csproj", "{9146E23A-6939-4BDF-9BB1-E0F5E7B97AAE}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SdkNetCore31Project", "SdkNetCore31Project\SdkNetCore31Project.csproj", "{B232D064-749F-4AA3-A70A-692694887388}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -88,6 +90,10 @@ Global
 		{9146E23A-6939-4BDF-9BB1-E0F5E7B97AAE}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{9146E23A-6939-4BDF-9BB1-E0F5E7B97AAE}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{9146E23A-6939-4BDF-9BB1-E0F5E7B97AAE}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B232D064-749F-4AA3-A70A-692694887388}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B232D064-749F-4AA3-A70A-692694887388}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B232D064-749F-4AA3-A70A-692694887388}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B232D064-749F-4AA3-A70A-692694887388}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE