Bump Serilog.Sinks.Async from 1.3.0 to 1.4.0 (PowerShell#975)

Bumps [Serilog.Sinks.Async](https://github.com/serilog/serilog-sinks-async) from 1.3.0 to 1.4.0.
- [Release notes](https://github.com/serilog/serilog-sinks-async/releases)
- [Commits](serilog/serilog-sinks-async@v1.3.0...v1.4.0)

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

src/PowerShellEditorServices/PowerShellEditorServices.csproj

@@ -19,7 +19,7 @@
     <PackageReference Include="Serilog" Version="2.8.0" />
     <PackageReference Include="Serilog.Sinks.Console" Version="3.1.1" />
     <PackageReference Include="Serilog.Sinks.File" Version="4.0.0" />
-    <PackageReference Include="Serilog.Sinks.Async" Version="1.3.0" />
+    <PackageReference Include="Serilog.Sinks.Async" Version="1.4.0" />
     <PackageReference Include="System.Runtime.Extensions" Version="4.3.1" />
     <PackageReference Include="Microsoft.Extensions.FileSystemGlobbing" Version="2.2.0" />
     <PackageReference Include="System.Runtime.InteropServices.RuntimeInformation" Version="4.3.0" />