optionally use backport of importlib resources for json import

plotting/roofline.py

 import plotly.graph_objs as go
 from dataclasses import dataclass
 import json
-import importlib
+
+try:
+    import importlib.resources as pkg_resources
+except ImportError:
+    # Try backported to PY<37 `importlib_resources`.
+    import importlib_resources as pkg_resources
 
 
 @dataclass
@@ -19,7 +24,7 @@ DEFAULT_MARKER = dict(size=10, color='green')
 
 
 def get_data(file_name="roofline_data.json"):
-    with importlib.resources.open_text(__package__, file_name) as file:
+    with pkg_resources.open_text(__package__, file_name) as file:
         data = json.load(file)
     return data
 

setup.py

@@ -23,7 +23,8 @@ setup(name="cb-util",
           "requests",
           "plotly",
           "kaleido",
-          "kadi-apy"
+          "kadi-apy",
+          "importlib_resources ; python_version<'3.7'",
       ],
       setup_requires=['pytest-runner'],
       tests_require=['pytest']