Remove unused reference

Author: IdamkinI

itext/itext.pdftest/itext.pdftest.csproj

@@ -47,9 +47,6 @@
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
-    <Reference Include="log4net">
-      <HintPath>$(SolutionDir)\packages\log4net.2.0.7\lib\net40-full\log4net.dll</HintPath>
-    </Reference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="itext\test\**\*.cs" />