fix one lingering ::pybind11 --> ::module target name (#603)

diff --git a/tools/pybind11Config.cmake.in b/tools/pybind11Config.cmake.in
index a4206c1..ae6d2da 100644
--- a/tools/pybind11Config.cmake.in
+++ b/tools/pybind11Config.cmake.in
@@ -71,7 +71,7 @@
 # Don't include targets if this file is being picked up by another
 # project which has already built this as a subproject
 #-----------------------------------------------------------------------------
-if(NOT TARGET ${PN}::pybind11)
+if(NOT TARGET ${PN}::module)
     include("${CMAKE_CURRENT_LIST_DIR}/${PN}Targets.cmake")
 
     find_package(PythonLibsNew ${PYBIND11_PYTHON_VERSION} MODULE REQUIRED)