Bump System.Net.Http from 4.3.0 to 4.3.4 in /source/ChromeDevTools

Bumps System.Net.Http from 4.3.0 to 4.3.4.

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

source/ChromeDevTools/MasterDevs.ChromeDevTools.Core.csproj

@@ -21,7 +21,7 @@
 
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="9.0.1" />
-    <PackageReference Include="System.Net.Http" Version="4.3.0" />
+    <PackageReference Include="System.Net.Http" Version="4.3.4" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard1.5'">