Make recommended updates to Cake plugin

Fixes #319

Author: AArnott

src/Cake.GitVersioning/Cake.GitVersioning.csproj

@@ -1,13 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net461</TargetFramework>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <Authors>Chris Crutchfield, Andrew Arnott</Authors>
     <Company>andarno</Company>
     <Description>Cake wrapper for Nerdbank.GitVersioning.  Stamps your assemblies with semver 2.0 compliant git commit specific version information and provides NuGet versioning information as well.</Description>
     <Copyright>Copyright © Andrew Arnott</Copyright>
     <PackageTags>git commit versioning version assemblyinfo</PackageTags>
+    <PackageIconUrl>https://cdn.jsdelivr.net/gh/cake-contrib/graphics/png/cake-contrib-medium.png</PackageIconUrl>
     <PackageProjectUrl>http://github.com/aarnott/Nerdbank.GitVersioning</PackageProjectUrl>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <SignAssembly>false</SignAssembly>
@@ -35,7 +36,7 @@
   </ItemDefinitionGroup>
 
   <ItemGroup>
-    <PackageReference Include="Cake.Core" Version="0.32.1" />
+    <PackageReference Include="Cake.Core" Version="0.33.0" />
     <PackageReference Include="DotNetMDDocs" Version="0.111.0" Condition=" '$(GenerateMarkdownApiDocs)' == 'true' " />
     <PackageReference Include="Nerdbank.GitVersioning.LKG" Version="1.6.20-beta-gfea83a8c9e" />
   </ItemGroup>