claude: remove stray debug print from dates() filter rewriting

[Liam-DeVoe]

Claude-written description

Removes a stray debug print(lo, hi) from DateStrategy.filter, left over from the original filter-rewriting-for-dates change in 6.115.1. It printed to stdout from library code whenever a dates() strategy's .filter() was rewritten from a partial(op.lt/le/eq/ge/gt, <date>) predicate.

Also adds a |st.dates| substitution to docs/prolog.rst (used by the new changelog entry), and a RELEASE.rst with a patch changelog entry.

The existing test_dates_filter_rewriting already covers the rewrite path; the filter-rewriting test suite passes. (One unrelated pre-existing failure in test_regex_filter_rewriting — a BytesWarning in the internal cache under python -bb — reproduces on unmodified master.)

Self-review note: enabling ruff T20 (flake8-print) for hypothesis/src would guard against this class of bug systemically (only reporting.py and extra/cli.py print legitimately), but was left out to keep this PR minimal.

[Zac-HD]

lgtm, but we might as well add the lint rule and open an issue for the bytes warning (assuming it's larger than is convenient to fix here)?