[3.2.x] Added missing mode="rb" argument to open() call in Client.post() example in docs.
[3.2.x] Added missing mode="rb" argument to open() call in Client.post() example in docs.

Backport of 509d266c6aae5e4d5738fe2a2cba0bde581aac2b from main

koordinates/django,koordinates/django,wkschwartz/django,wkschwartz/django,wkschwartz/django,koordinates/django,wkschwartz/django,koordinates/django