add importlib_metadata as dependency (#227)

* add importlib_metadata as dependency

* add quote

Author: njzjz

setup.py

@@ -12,7 +12,7 @@
         readme = f.read()
 
 # install_requires = ['xml']
-install_requires=['numpy>=1.14.3', 'monty', 'scipy', 'h5py', 'wcmatch']
+install_requires=['numpy>=1.14.3', 'monty', 'scipy', 'h5py', 'wcmatch', 'importlib_metadata>=1.4; python_version < "3.8"']
 
 setuptools.setup(
     name="dpdata",