build(deps): bump NLog from 4.7.7 to 4.7.8 (#678)

Bumps [NLog](https://github.com/NLog/NLog) from 4.7.7 to 4.7.8.
- [Release notes](https://github.com/NLog/NLog/releases)
- [Changelog](https://github.com/NLog/NLog/blob/dev/CHANGELOG.md)
- [Commits](https://github.com/NLog/NLog/commits)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

src/Splat.NLog/Splat.NLog.csproj

@@ -10,7 +10,7 @@
     <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="NLog" Version="4.7.7" />
+    <PackageReference Include="NLog" Version="4.7.8" />
     <PackageReference Include="System.Collections.Immutable" Version="5.0.0" />
   </ItemGroup>
   <ItemGroup>