fix(deps): raise tldextract floor to >=5.3.0 to avoid AttributeError on same-domain enqueue

[anxkhn]

_domain_under_public_suffix in src/crawlee/_utils/urls.py reads the
top_domain_under_public_suffix property of tldextract's ExtractResult:

return _get_tld_extractor().extract_str(host).top_domain_under_public_suffix

That property was added in tldextract 5.3.0 (2025-04-21), but the dependency
constraint in pyproject.toml is still tldextract>=5.1.0. Any environment that
resolves tldextract into the permitted 5.1.0-5.2.x range therefore raises

AttributeError: 'ExtractResult' object has no attribute 'top_domain_under_public_suffix'

the first time registrable-domain matching runs, i.e. on the same-domain
enqueue strategy (_matches_enqueue_strategy). The bundled uv.lock pins a
newer tldextract, so CI always runs a version that has the property and never
exercises the older versions the metadata still allows.

This bumps the floor to >=5.3.0 to match the code. top_domain_under_public_suffix
is the only tldextract result property used anywhere in src/, so 5.3.0 is
exactly the version that introduced the API the code relies on. It is a
metadata-only change; the currently resolved tldextract already satisfies the
new floor, so uv.lock needs no re-resolution beyond the mirrored specifier
line.

Issues

• Not applicable (no existing issue).

Testing

• uv lock --check passes (lockfile stays consistent with the new floor).
• uv run pytest tests/unit/_utils/test_urls.py -> 28 passed, including the
  same-domain parametrizations that exercise the property.
• uv run poe lint passes (ruff format check + ruff check).
• No new test: the change is pure dependency metadata and cannot be driven
  red->green against the resolved tldextract (which already has the property);
  the same-domain path is already covered by the existing URL filter tests.

Checklist

• CI passed

[vdusek]

LGTM