Fix config file

src/Workspaces/CoreTest/app.config

 <?xml version="1.0" encoding="utf-8" ?>
 <configuration>
   <runtime>
-    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
-      <dependentAssembly>
-        <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
-        <bindingRedirect oldVersion="1.0.0.0-1.65535.65535.65535" newVersion="1.1.36.0"/>
-      </dependentAssembly>
-    </assemblyBinding>
-    <configSections>
-      <!-- Microsoft.Build.Engine instead of Microsoft.Build here because a task run under Microsoft.Build may load Microsoft.Build.Engine, which will attempt to read this section. -->
-      <section name="msbuildToolsets" type="Microsoft.Build.BuildEngine.ToolsetConfigurationSection, Microsoft.Build.Engine, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
-    </configSections>
-    <runtime>
-      <DisableFXClosureWalk enabled="true" />
-      <generatePublisherEvidence enabled="false" />
       <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
         <dependentAssembly>
           <assemblyIdentity name="Microsoft.Build.Framework" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
@@ -45,5 +32,4 @@
         </dependentAssembly>
       </assemblyBinding>
     </runtime>
-  </runtime>
 </configuration>