[ENH] - Add openpyxl to scipy-notebook to support .xlsx Excel files

[dietmar]

What docker image(s) is this feature applicable to?

scipy-notebook

What changes are you proposing?

Add the openpyxl package to the image.

Currently, the pandas function read_excel can only read old-style .xls files but not new-style .xlsx files, because the scipy-notebook image does contain the package xlrd, but not openpyxl.
Since pandas 1.3.0, read_excel uses xlrd for old-style .xls files only, for new-style .xlsx files openpyxl is required, see the following links:

• What's new in pandas 1.3.0: https://pandas.pydata.org/pandas-docs/version/1.3.0/whatsnew/v1.3.0.html
• Pandas issue for this topic: Deprecate using xlrd engine in favor of openpyxl pandas-dev/pandas#28547
• Pandas documentation for read_excel (under "engine"): https://pandas.pydata.org/docs/reference/api/pandas.read_excel.html

How does this affect the user?

"New-style" .xlsx files are IMO very common (and more common than .xls these days), so including the capability to work with such files per default makes a lot of sense.

The scipy-notebook image seems the right place for this, because this is where all the Python dependencies are added (such as xlrd). Initially I came across this issue using the datascience-notebook image, but that is based off scipy-notebook.

Anything else?

I'll be working on a pull request myself right away.