Update NUnit packages.

Author: mrworkman

src/LinqToExcel.Tests/LinqToExcel.Tests.csproj

@@ -7,11 +7,11 @@
 
   <ItemGroup>
     <PackageReference Include="log4net" Version="2.0.8" />
-    <PackageReference Include="NUnit" Version="3.9.0" />
-    <PackageReference Include="NUnit.Console" Version="3.7.0" />
-    <PackageReference Include="NUnit.ConsoleRunner" Version="3.7.0" />
-    <PackageReference Include="NUnit.Extension.VSProjectLoader" Version="3.6.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="3.9.0" />
+    <PackageReference Include="NUnit" Version="3.10.1" />
+    <PackageReference Include="NUnit.Console" Version="3.8.0" />
+    <PackageReference Include="NUnit.ConsoleRunner" Version="3.8.0" />
+    <PackageReference Include="NUnit.Extension.VSProjectLoader" Version="3.8.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="3.10.0" />
   </ItemGroup>
 
   <!-- Run tests for .Net 3.5 in x64 mode, by default -->