add `packaging` to setup.py file?
After installing plotly==5.13.1, `import plotly.io` failed with the below error due to `packaging` not being installed in my python 3.6 env by default:

```
      import plotly.io as pio
    File "/app/.heroku/python/lib/python3.6/site-packages/plotly/__init__.py", line 35, in <module>
      from plotly import (
    File "/app/.heroku/python/lib/python3.6/site-packages/plotly/io/__init__.py", line 12, in <module>
      from ._renderers import renderers, show
    File "/app/.heroku/python/lib/python3.6/site-packages/plotly/io/_renderers.py", line 7, in <module>
      from packaging.version import Version
ModuleNotFoundError: No module named 'packaging'```

diff --git a/packages/python/plotly/setup.py b/packages/python/plotly/setup.py
index 1a8f20573..3614cb970 100644
--- a/packages/python/plotly/setup.py
+++ b/packages/python/plotly/setup.py
@@ -556,7 +556,7 @@ setup(
     data_files=[
         ("etc/jupyter/nbconfig/notebook.d", ["jupyterlab-plotly.json"]),
     ],
-    install_requires=["tenacity>=6.2.0"],
+    install_requires=["tenacity>=6.2.0", "packaging"],
     zip_safe=False,
     cmdclass=dict(
         build_py=js_prerelease(versioneer_cmds["build_py"]),
['packages/python/plotly/setup.py']