fix path module. os.path->pathlib

[hrsano645]

Changes in this pull request:

(only jp document)

• Changed the libraries used in the documentation. os.path -> pathlib

[ryu22e]

Hello. It seems to me that this PR can be merged by addressing the following comment, what is stopping you?

https://github.com/DjangoGirls/tutorial/pull/1766#discussion_r1070236181

I had a participant at one of my events who was stumped by this code. It would be helpful if you could merge it as soon as possible.

[ryu22e]

Hello. Since the creator of this PR seems to be busy, I have created a PR on my end. Could someone please review it for me? https://github.com/DjangoGirls/tutorial/pull/1786

[das-g]

Fixed with #1786 & #1787.