Release v0.20.3: polars integration cleanup, docs updates, bugfixes

What's Changed

• update dtype api reference docs by @cosmicBboy in #1745
• handle deprecated methods/arguments in polars v1 by @cosmicBboy in #1746
• handle case when pandera is run with optimized python mode by @cosmicBboy in #1749

Full Changelog: v0.20.2...v0.20.3