fix: raise TypeError for unrecognised messages in normalize_midi_messages

[m-zandi]

What this PR does

Fixes the silent data-loss bug in normalize_midi_messages() where
unrecognised MIDI messages (wrong tuple length, bare bytes, unknown type,
etc.) were silently dropped from the output list.

Changes

• pedalboard/midi_utils.py — Added else branch that raises TypeError
  with the index and repr of the offending element, so callers get an
  immediate, actionable error instead of a shorter-than-expected list.
• tests/test_midi_utils.py — Added parametrized regression tests covering
  1-tuples, 3-tuples, bare bytes, bare integers, and None.

Closes

Closes #489

How to test

pytest tests/test_midi_utils.py -v

All new tests should pass. The existing test_mido_normalization test is
unaffected.

Before / After

Before:

result = normalize_midi_messages([(bytes([0x90, 60, 64]),)])
print(result)  # [] — silently dropped, no error

After:

result = normalize_midi_messages([(bytes([0x90, 60, 64]),)])
# TypeError: Could not interpret MIDI message at index 0: (b'\x90<@',).
# Expected an object with 'bytes()' and 'time' attributes (e.g. mido.Message),
# or a 2-element tuple/list of (message_bytes, timestamp_seconds).