Update build and test dependencies

Author: FObermaier

src/Directory.Build.props

@@ -99,7 +99,7 @@
 
   <ItemGroup>
     <!-- SourceLink adds stuff to let debuggers step into our code. -->
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All" />
   </ItemGroup>
 
 </Project>

test/Directory.Build.props

@@ -5,8 +5,8 @@
 
   <ItemGroup>
     <PackageReference Include="nunit" Version="3.12.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="3.16.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.5.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
   </ItemGroup>
 
 </Project>