Update Titanium.Web.Proxy.IntegrationTests.csproj

fix

Author: honfika

tests/Titanium.Web.Proxy.IntegrationTests/Titanium.Web.Proxy.IntegrationTests.csproj

@@ -18,6 +18,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
     <PackageReference Include="MSTest.TestAdapter" Version="2.0.0" />
     <PackageReference Include="MSTest.TestFramework" Version="2.0.0" />
+    <PackageReference Include="System.IO.Pipelines" Version="4.7.1" />
   </ItemGroup>
 
   <ItemGroup>