Bump System.Data.SqlClient in /src/NuGet.Services.Sql (#418)

Bumps [System.Data.SqlClient](https://github.com/dotnet/corefx) from 4.8.5 to 4.8.6.
- [Release notes](https://github.com/dotnet/corefx/releases)
- [Commits](https://github.com/dotnet/corefx/commits)

---
updated-dependencies:
- dependency-name: System.Data.SqlClient
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/NuGet.Services.Sql/NuGet.Services.Sql.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
-    <PackageReference Include="System.Data.SqlClient" Version="4.8.5" />
+    <PackageReference Include="System.Data.SqlClient" Version="4.8.6" />
   </ItemGroup>
 
   <ItemGroup>