build(deps): bump MediatR from 12.3.0 to 12.4.0

Bumps [MediatR](https://github.com/jbogard/MediatR) from 12.3.0 to 12.4.0.
- [Release notes](https://github.com/jbogard/MediatR/releases)
- [Commits](jbogard/MediatR@v12.3.0...v12.4.0)

---
updated-dependencies:
- dependency-name: MediatR
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Directory.Packages.props

@@ -24,7 +24,7 @@
     <PackageVersion Include="FluentValidation" Version="11.9.0" />
     <PackageVersion Include="Mapster" Version="7.4.0" />
     <PackageVersion Include="Mapster.DependencyInjection" Version="1.0.1" />
-    <PackageVersion Include="MediatR" Version="12.3.0" />
+    <PackageVersion Include="MediatR" Version="12.4.0" />
     <PackageVersion Include="MediatR.Extensions.Autofac.DependencyInjection" Version="12.0.0" />
     <PackageVersion Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.7" />
     <PackageVersion Include="Microsoft.EntityFrameworkCore.Sqlite" Version="8.0.7" />