pythonPackages.pysam: add libdeflate and enable tests
pythonPackages.pysam: add libdeflate and enable tests

Some tests still fail due to upstream reasons so we skip those.

Note also that we are not using nix's pytestCheckHook due to
pysam detecting how it's loaded which conflicts with how
pytestCheckHook runs tests. In addition, the selection mode used
by disabledTests causes more tests than the failing ones to be
skipped, which is undesired.
See the discussion in https://github.com/NixOS/nixpkgs/pull/100823

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