feature: add retry

[georgik]

Current download script failed with:

Traceback (most recent call last):
  File ".../python3.13/site-packages/urllib3/response.py", line 761, in _update_chunk_length
    self.chunk_left = int(line, 16)
                      ~~~^^^^^^^^^^
ValueError: invalid literal for int() with base 16: b''

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File ".../python3.13/site-packages/urllib3/response.py", line 444, in _error_catcher
    yield
  File ".../python3.13/site-packages/urllib3/response.py", line 828, in read_chunked
    self._update_chunk_length()
    ~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File ".../python3.13/site-packages/urllib3/response.py", line 765, in _update_chunk_length
    raise InvalidChunkLength(self, line)
urllib3.exceptions.InvalidChunkLength: InvalidChunkLength(got length b'', 0 bytes read)

Solution: Add retry mechanism to make download more resilient.