Add 3.12 CI jobs

[NicolasHug]

The next version should support 3.12 so we should make sure to cover that in our CI jobs.

Let's also merge #8119 and #8280

Just delaying this a bit until #8292 is managed.

Note: 3.8 removal won't happen before 2.4 pytorch/pytorch#120718

[hmaarrfk]

Very excited about this.

I'm not sure if the pytorch deprecation warnings were handled by pytorch itself, but I wanted to point to an obscur error message that we "addressed" at conda-forge.

the AST in python 3.12 issues a few warnings to pytorch, so with the strict warning catching of some of the tests, the test suite doesn't pass with 3.12.

We relaxed them with a small patch

https://github.com/conda-forge/torchvision-feedstock/blob/b88453f2b521986e5f3d52ac4e626ccf94046adb/recipe/ignore_python312_deprecation_warnings.patch

diff --git a/test/test_transforms_v2_refactored.py b/test/test_transforms_v2_refactored.py
index e18beb35a4..142e3f2d43 100644
--- a/test/test_transforms_v2_refactored.py
+++ b/test/test_transforms_v2_refactored.py
@@ -416,7 +416,10 @@ def reference_affine_bounding_boxes_helper(bounding_boxes, *, affine_matrix, new
 
 
 # turns all warnings into errors for this module
-pytestmark = pytest.mark.filterwarnings("error")
+pytestmark = [
+    pytest.mark.filterwarnings("error"),
+    pytest.mark.filterwarnings("ignore::DeprecationWarning"),
+]
 
 
 class TestResize:

[NicolasHug]

Thanks a lot for the headsup @hmaarrfk , I'm observing the same issue in #8299. Let's see if ffd7bd5 can address that.

[NicolasHug]

All done in #8299, we can close this. Thanks @hmaarrfk for the PRs and help with the warnings!