phase 1: add <LangVersion>7.3</LangVersion>

Author: thangchung

.vs/netcorekit/v16/.suo

@@ -6,6 +6,7 @@
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)netcorekit.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
     <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
+    <LangVersion>7.3</LangVersion>
   </PropertyGroup>
 
   <PropertyGroup>

build/packages.props

@@ -93,6 +93,13 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NetCoreKit.RestTemplate.Sta
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NetCoreKit.Infrastructure.EfCore.Tests", "src\NetCoreKit.Infrastructure.EfCore.Tests\NetCoreKit.Infrastructure.EfCore.Tests.csproj", "{B4C4A9F0-00F0-45D8-8A82-60870EBD17A3}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "build", "build", "{4F50C243-D572-4F13-B481-FC2E68822882}"
+	ProjectSection(SolutionItems) = preProject
+		build\common.props = build\common.props
+		build\netcorekit.snk = build\netcorekit.snk
+		build\packages.props = build\packages.props
+	EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU