Update System.Memory dependency for netstandard2.0 target.

Update test project dependencies.

Author: wo80

CSparse.Tests/CSparse.Tests.csproj

@@ -41,9 +41,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="NUnit" Version="4.2.2" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="NUnit" Version="4.4.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="5.2.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
   </ItemGroup>
 
   <ItemGroup>

CSparse/CSparse.csproj

@@ -44,7 +44,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Memory" Version="4.5.5" Condition="'$(TargetFramework)' == 'netstandard2.0'" />
+    <PackageReference Include="System.Memory" Version="4.6.3" Condition="'$(TargetFramework)' == 'netstandard2.0'" />
   </ItemGroup>
 
   <ItemGroup>