Bump Microsoft.EntityFrameworkCore.SqlServer from 6.0.12 to 6.0.15 (#60)

Bumps [Microsoft.EntityFrameworkCore.SqlServer](https://github.com/dotnet/efcore) from 6.0.12 to 6.0.15.
- [Release notes](https://github.com/dotnet/efcore/releases)
- [Commits](dotnet/efcore@v6.0.12...v6.0.15)

---
updated-dependencies:
- dependency-name: Microsoft.EntityFrameworkCore.SqlServer
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

src/Bunkograph.Web/Bunkograph.Web.csproj

@@ -17,7 +17,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.SpaProxy" Version="6.0.12" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="6.0.12" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="6.0.15" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="6.0.12">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>