[cmake] adds shell-sourceable file with python module info

cmake/modules/DunePybindxiInstallPythonPackage.cmake

@@ -53,6 +53,7 @@ function(dune_pybindxi_install_python_package)
                               "${CMAKE_CURRENT_BINARY_DIR}/${rel_fn}")
     endforeach()
     configure_file(${PYINST_PATH}/setup.py.in ${PYINST_PATH}/setup.py)
+    configure_file(${PYINST_PATH}/version.sh.in ${PYINST_PATH}/version.sh)
     set(PYINST_FULLPATH ${CMAKE_CURRENT_BINARY_DIR}/${PYINST_PATH})
     set(PYINST_PUREPYTHON TRUE)
   elseif(EXISTS ${PYINST_FULLPATH}/setup.py)

python/version.sh.in

+${dune-xt_VERSION}