Bump Microsoft.AspNetCore.All in /tests/MySqlConnector.Performance

Bumps [Microsoft.AspNetCore.All](https://github.com/aspnet/AspNetCore) from 2.1.4 to 2.1.15.
- [Release notes](https://github.com/aspnet/AspNetCore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/main/docs/ReleasePlanning.md)
- [Commits](dotnet/aspnetcore@2.1.4...v2.1.15)

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.All
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

tests/MySqlConnector.Performance/MySqlConnector.Performance.csproj

@@ -12,7 +12,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.1.4" />
+    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.1.15" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(Configuration)' != 'Baseline' ">