Update csproj to target netstandard 2.0

Author: gertjvr

src/Serilog.Extensions.Logging/Serilog.Extensions.Logging.csproj

@@ -4,7 +4,7 @@
     <Description>Serilog provider for Microsoft.Extensions.Logging</Description>
     <VersionPrefix>1.4.1</VersionPrefix>
     <Authors>Microsoft;Serilog Contributors</Authors>
-    <TargetFrameworks>net45;net46;netstandard1.3</TargetFrameworks>
+    <TargetFrameworks>net45;net46;netstandard1.3,netstandard2.0</TargetFrameworks>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <AssemblyName>Serilog.Extensions.Logging</AssemblyName>
@@ -22,20 +22,32 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="1.0.0" />
     <PackageReference Include="Serilog" Version="2.3.0" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">
     <Reference Include="System.Runtime" />
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="1.0.0" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net46' ">
     <Reference Include="System.Runtime" />
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="1.0.0" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="1.0.0" />
+    <Compile Remove="SerilogLoggerServicesExtensions.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="2.0.0-preview2-final" />
+    <PackageReference Include="NETStandard.Library" Version="2.0.0-preview2-25401-01" />
+    <Compile Remove="SerilogLoggerFactoryExtensions.cs" />
   </ItemGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'net46' ">
@@ -46,4 +58,8 @@
     <DefineConstants>$(DefineConstants);ASYNCLOCAL</DefineConstants>
   </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+    <DefineConstants>$(DefineConstants);ASYNCLOCAL</DefineConstants>
+  </PropertyGroup>
+
 </Project>