Bump LightningDB from 0.14.1 to 0.15.0

Bumps [LightningDB](https://github.com/CoreyKaylor/Lightning.NET) from 0.14.1 to 0.15.0.
- [Release notes](https://github.com/CoreyKaylor/Lightning.NET/releases)
- [Commits](CoreyKaylor/Lightning.NET@v0.14.1...v0.15.0)

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

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

src/contrib/cluster/Akka.DistributedData.LightningDB/Akka.DistributedData.LightningDB.csproj

@@ -15,7 +15,7 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="LightningDB" Version="0.14.1"/>
+        <PackageReference Include="LightningDB" Version="0.15.0"/>
     </ItemGroup>
 
     <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">