Bump the mstest group with 1 update

Bumps Microsoft.NET.Test.Sdk from 17.12.0 to 18.5.1

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.5.1
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: mstest
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.5.1
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: mstest
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tests/Microsoft.Graph.DotnetCore.Test/Microsoft.Graph.DotnetCore.Test.csproj

@@ -16,7 +16,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">