don't append python bindings src path to module version

this produces warning when running 'python3 setup.py egg_info':

  setuptools/dist.py:501:  UserWarning: The version specified
  ('<ugly string with version + path>') is an invalid version.

so, just keep only standard version number in x.y.z format

bindings/python/CMakeLists.txt

@@ -116,7 +116,7 @@ if (python-egg-info)
 	configure_file(${SETUP_PY_IN} ${SETUP_PY} @ONLY)
 
 	add_custom_command(OUTPUT ${OUTPUT}
-		COMMAND ${Python3_EXECUTABLE} ${SETUP_PY} egg_info -b "${CMAKE_CURRENT_SOURCE_DIR}"
+		COMMAND ${Python3_EXECUTABLE} ${SETUP_PY} egg_info
 		COMMAND ${CMAKE_COMMAND} -E touch ${OUTPUT}
 		DEPENDS ${DEPS}
 	)