v1.0.0b1 pre-release (many refactor)

What's Changed

• Improvement by @vwxyzjn in #2
• fix hts-rl paper link by @ChufanSuki in #3
• Remove the legacy last action rewards script by @vwxyzjn in #7
• add grad accum for ppo + envpool + impala atari wrapper by @51616 in #8
• Add actor threads example by @vwxyzjn in #6

New Contributors

• @vwxyzjn made their first contribution in #2
• @ChufanSuki made their first contribution in #3
• @51616 made their first contribution in #8

Full Changelog: v0.0.1...v1.0.0b1