Convert sets to sorted lists prior to sampling

This is because sampling of sets has been deprecated in Python 3.9. I used
sorted() instead of list() so that things are deterministic.

tests/core/pyspec/eth2spec/test/altair/transition/test_transition.py

@@ -281,7 +281,7 @@ def test_transition_with_random_three_quarters_participation(state, fork_epoch,
         assert committee_len >= 4
         filter_len = committee_len // 4
         participant_count = committee_len - filter_len
-        return rng.sample(indices, participant_count)
+        return rng.sample(sorted(indices), participant_count)
 
     yield from _run_transition_test_with_attestations(
         state,
@@ -304,7 +304,7 @@ def test_transition_with_random_half_participation(state, fork_epoch, spec, post
         assert committee_len >= 2
         filter_len = committee_len // 2
         participant_count = committee_len - filter_len
-        return rng.sample(indices, participant_count)
+        return rng.sample(sorted(indices), participant_count)
 
     yield from _run_transition_test_with_attestations(
         state,

tests/core/pyspec/eth2spec/test/altair/unittests/validator/test_validator.py

@@ -59,7 +59,7 @@ def test_is_assigned_to_sync_committee(spec, state):
     if disqualified_pubkeys:
         sample_size = 3
         assert validator_count >= sample_size
-        some_pubkeys = rng.sample(disqualified_pubkeys, sample_size)
+        some_pubkeys = rng.sample(sorted(disqualified_pubkeys), sample_size)
         for pubkey in some_pubkeys:
             validator_index = active_pubkeys.index(pubkey)
             is_current = spec.is_assigned_to_sync_committee(

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py

@@ -200,7 +200,7 @@ def run_with_participation(spec, state, participation_fn):
 @spec_state_test
 def test_almost_empty_attestations(spec, state):
     rng = Random(1234)
-    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, 1))
+    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(sorted(comm), 1))
 
 
 @with_all_phases
@@ -208,14 +208,14 @@ def test_almost_empty_attestations(spec, state):
 @leaking()
 def test_almost_empty_attestations_with_leak(spec, state):
     rng = Random(1234)
-    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, 1))
+    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(sorted(comm), 1))
 
 
 @with_all_phases
 @spec_state_test
 def test_random_fill_attestations(spec, state):
     rng = Random(4567)
-    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) // 3))
+    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(sorted(comm), len(comm) // 3))
 
 
 @with_all_phases
@@ -223,14 +223,14 @@ def test_random_fill_attestations(spec, state):
 @leaking()
 def test_random_fill_attestations_with_leak(spec, state):
     rng = Random(4567)
-    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) // 3))
+    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(sorted(comm), len(comm) // 3))
 
 
 @with_all_phases
 @spec_state_test
 def test_almost_full_attestations(spec, state):
     rng = Random(8901)
-    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) - 1))
+    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(sorted(comm), len(comm) - 1))
 
 
 @with_all_phases
@@ -238,7 +238,7 @@ def test_almost_full_attestations(spec, state):
 @leaking()
 def test_almost_full_attestations_with_leak(spec, state):
     rng = Random(8901)
-    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(comm, len(comm) - 1))
+    yield from run_with_participation(spec, state, lambda slot, comm_index, comm: rng.sample(sorted(comm), len(comm) - 1))
 
 
 @with_all_phases

tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_on_block.py

@@ -38,7 +38,7 @@ def _drop_random_one_third(_slot, _index, indices):
     assert committee_len >= 3
     filter_len = committee_len // 3
     participant_count = committee_len - filter_len
-    return rng.sample(indices, participant_count)
+    return rng.sample(sorted(indices), participant_count)
 
 
 @with_all_phases