Convert sets to sorted lists prior to sampling

[jtraglia]

PR Description

According the docs for random.sample:

Deprecated since version 3.9: In the future, the population must be a sequence. Instances of set are no longer supported. The set must first be converted to a list or tuple, preferably in a deterministic order so that the sample is reproducible.

I used sorted() instead of list() to make things deterministic.

Fixed Warnings

tests/core/pyspec/eth2spec/test/altair/transition/test_transition.py: 282 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/altair/transition/test_transition.py:307: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    return rng.sample(indices, participant_count)

tests/core/pyspec/eth2spec/test/altair/transition/test_transition.py: 282 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/altair/transition/test_transition.py:284: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    return rng.sample(indices, participant_count)

tests/core/pyspec/eth2spec/test/altair/unittests/validator/test_validator.py::test_is_assigned_to_sync_committee
tests/core/pyspec/eth2spec/test/altair/unittests/validator/test_validator.py::test_is_assigned_to_sync_committee
tests/core/pyspec/eth2spec/test/altair/unittests/validator/test_validator.py::test_is_assigned_to_sync_committee
  /consensus-specs/tests/core/pyspec/eth2spec/test/altair/unittests/validator/test_validator.py:62: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    some_pubkeys = rng.sample(disqualified_pubkeys, sample_size)

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py:203: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, 1))

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py:211: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, 1))

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py:218: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) // 3))

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py:226: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) // 3))

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py:233: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) - 1))

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py:241: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) - 1))

tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py: 64 warnings
  /consensus-specs/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py:41: DeprecationWarning: Sampling from a set deprecated
  since Python 3.9 and will be removed in a subsequent version.
    return rng.sample(indices, participant_count)

[ralexstokes]

nice one, thanks!

[hwwhww]

Thank you! @jtraglia