Fixed typo in tc_project_app.plcproj

solution/tc_project_app/tc_project_app.plcproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <FileVersion>1.0.0.0</FileVersion>
@@ -131,6 +131,8 @@
       <SubType>Code</SubType>
     </Compile>
     <Compile Include="Test\standard_library_tests\tcUNIT_STD_LIB_RUN.TcPOU">
+      <SubType>Code</SubType>
+    </Compile>
     <Compile Include="Test\app_tests\tcUNIT_APP_RUN.TcPOU">
       <SubType>Code</SubType>
     </Compile>