pin numpy for Python 3.8

[pmeier]

Fixes #7638

cc @seemethere

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/vision/7639

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❌ 3 New Failures

As of commit 02b7975:

NEW FAILURES - The following jobs have failed:

• unittests-linux (3.11, linux.12xlarge, cpu) / linux-job (gh)
• unittests-macos (3.8, macos-m1-12) / macos-job (gh)
• unittests-macos (3.9, macos-12) / macos-job (gh)

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[NicolasHug]

stamping

[pmeier]

Something weird is going on for Linux / 3.11. Somehow,

vision/test/test_videoapi.py

Lines 13 to 19 in 01b9faa

	try:
	import av
	# Do a version test too
	torchvision.io.video._check_av_available()
	except ImportError:
	av = None

this leaves us with something like av = ImportError. In turn, the skips, e.g.

vision/test/test_videoapi.py

Line 54 in 01b9faa

@pytest.mark.skipif(av is None, reason="PyAV unavailable")

don't work properly and we get errors like

Traceback (most recent call last):
  File "/work/test/test_videoapi.py", line 127, in test_frame_reading_mem_vs_file
    reader = VideoReader(full_path)
             ^^^^^^^^^^^^^^^^^^^^^^
  File "/work/torchvision/io/video_reader.py", line 171, in __init__
    self.container = av.open(src, metadata_errors="ignore")
                     ^^^^^^^
AttributeError: 'ImportError' object has no attribute 'open'

I doubt that it has something to do with this PR, but even if it has, the CI is less red afterwards. Will look into that next.

[github-actions]

Hey @pmeier!

You merged this PR, but no labels were added. The list of valid labels is available at https://github.com/pytorch/vision/blob/main/.github/process_commit.py