Testing against podman-next breaks test_container_mounts

[inknos]

This recent upstream breaking change impacted the tests containers/podman#25942.

Probably podman-py testing should reflect only podman release branches

Impacts:
#513
#544
#546
#540

And other test runs

[inknos]

cc: @lsm5

[inknos]

Probably podman-py testing should reflect only podman release branches

A better solution could be to duplicate the tests runs and run the test suite against distribution podman and podman-next. podman-next is used to test against features that are coming in the next release, so it's crucial to be able to test against upstream changes sometimes.
By making use of pytest skipping we could run the scenarios for stable features and for future features when we have one (which would also be a considerably small run).