fix(node): fix text handling for bytes-like callbacks

[zahid-arbisoft]

Summary

Fix a segfault in Node.text when the parse source comes from a callback returning a bytes-like object.

Related to #435.

What changed

• Updated the callable-source branch in node_get_text to use the normalized bytearray buffer when computing length and reading bytes.
• Added regression coverage for callback sources returning:
  • bytes
  • bytearray
  • memoryview

Why

The previous implementation accepted bytes-like callback results, but later treated the original callback return value as if it were always a bytes object. That could segfault when Node.text was accessed.

This change addresses a node_get_text crash in the same area discussed in #435.

Testing

• python -m unittest discover -s tests -v

[ObserverOfTime]

The added test case fails sometimes:

======================================================================
ERROR: test_text_with_callback_source (tests.test_node.TestNode.test_text_with_callback_source) (type='bytes')
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/runner/work/py-tree-sitter/py-tree-sitter/tests/test_node.py", line 484, in test_text_with_callback_source
    self.assertEqual(tree.root_node.text, source_code)
                     ^^^^^^^^^^^^^^^^^^^
TypeError: cannot convert 'NoneType' object to bytearray

======================================================================
ERROR: test_text_with_callback_source (tests.test_node.TestNode.test_text_with_callback_source) (type='bytearray')
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/runner/work/py-tree-sitter/py-tree-sitter/tests/test_node.py", line 484, in test_text_with_callback_source
    self.assertEqual(tree.root_node.text, source_code)
                     ^^^^^^^^^^^^^^^^^^^
TypeError: cannot convert 'NoneType' object to bytearray

======================================================================
ERROR: test_text_with_callback_source (tests.test_node.TestNode.test_text_with_callback_source) (type='memoryview')
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/runner/work/py-tree-sitter/py-tree-sitter/tests/test_node.py", line 484, in test_text_with_callback_source
    self.assertEqual(tree.root_node.text, source_code)
                     ^^^^^^^^^^^^^^^^^^^
TypeError: cannot convert 'NoneType' object to bytearray