build(deps): bump Mindscape.Raygun4Net from 5.12.0 to 5.13.0

Bumps [Mindscape.Raygun4Net](https://github.com/MindscapeHQ/raygun4net) from 5.12.0 to 5.13.0.
- [Release notes](https://github.com/MindscapeHQ/raygun4net/releases)
- [Commits](https://github.com/MindscapeHQ/raygun4net/commits)

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

src/Splat.Raygun/Splat.Raygun.csproj

@@ -25,7 +25,7 @@
     </When>
     <When Condition=" $(TargetFramework.StartsWith('net4')) ">
       <ItemGroup>
-        <PackageReference Include="Mindscape.Raygun4Net" Version="5.12.0" />
+        <PackageReference Include="Mindscape.Raygun4Net" Version="5.13.0" />
       </ItemGroup>
     </When>
   </Choose>