Bump System.Threading.Tasks.Extensions from 4.5.3 to 4.5.4 in /src

Bumps [System.Threading.Tasks.Extensions](https://github.com/dotnet/corefx) from 4.5.3 to 4.5.4.
- [Release notes](https://github.com/dotnet/corefx/releases)
- [Commits](https://github.com/dotnet/corefx/commits)

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

src/StreamJsonRpc/StreamJsonRpc.csproj

@@ -32,7 +32,7 @@
     <PackageReference Include="System.Net.WebSockets" Version="4.3.0" />
     <PackageReference Include="System.Reflection.Emit" Version="4.7.0" />
     <PackageReference Include="System.Threading.Tasks.Dataflow" Version="4.11.1" PrivateAssets="compile" />
-    <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.3" />
+    <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
     <PackageReference Include="XliffTasks" Version="1.0.0-beta.19253.2" PrivateAssets="all" />
   </ItemGroup>
   <ItemGroup>