Bump Microsoft.AspNetCore.Mvc.Testing from 9.0.0 to 9.0.14

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.Mvc.Testing
  dependency-version: 9.0.14
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

backend/tests/Agon.Integration.Tests/Agon.Integration.Tests.csproj

@@ -10,7 +10,7 @@
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="8.0.1" />
     <PackageReference Include="FluentAssertions" Version="8.8.0" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.14" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="9.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="NSubstitute" Version="5.3.0" />