chore: require playwright>=1.60 in CI and unskip 1.60 tests (#313)

chore: require playwright>=1.60 in CI and unskip 1.60 tests

Playwright Python 1.60 has been released, so the tests gated on it can
now run. Pin the dev dependency in local-requirements.txt so CI installs
a compatible version; the package’s runtime requirement is unchanged.
Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

test(connect_options): adapt to Playwright 1.59.1+ connect() API

BrowserType.connect() renamed its first parameter from ws_endpoint to
endpoint (positional) in microsoft/playwright-python#3050. The test
also needs to look at stderr from the subprocess pytester run, since
the WebSocket error log lands there.
Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

test: set PYTHONIOENCODING=utf-8 for pytester subprocesses

Pytester decodes subprocess stdout as utf-8, but on Windows the default
stdout encoding is cp1252. When Playwright’s assertion failure messages
contain non-ASCII characters (e.g. unicode arrows / multiplication
signs), pytester raises UnicodeDecodeError. Force utf-8 in child Python
processes.
Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com