(#372) update recommended cake version to 5.0.0 (#373)

Author: nils-a

src/Guidelines/build/RecommendedCakeVersion.targets

@@ -15,7 +15,7 @@
             <CakeReferenceToCheck Include="cake.testing" />
         </ItemGroup>
         <PropertyGroup>
-            <RecommendedCakeVersion>4.0.0</RecommendedCakeVersion>
+            <RecommendedCakeVersion>5.0.0</RecommendedCakeVersion>
         </PropertyGroup>
 
         <RecommendedCakeVersion