Jiminy release 1.8.5

[duburcqa]

• [core] Full support of serialization of 'Robot'. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770) ([core] Full support of serialization for 'Robot'. #775)
• [core] Do NOT use 'enable_shared_from_this' if not strictly necessary. ([core] Full support of serialization for 'Robot'. #775)
• [core] Rename macro 'PRINT_WARNING' in 'JIMINY_WARNING' to avoid conflicts. ([core] Full support of serialization for 'Robot'. #775)
• [python/simulator] 'plot' now support multi-robot simulations. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770)
• [gym/common] Speedup 'PDController' env pipeline block. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770)
• [gym/common] Speedup 'StackedJiminyEnv' wrapper. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770)
• [gym/common] More generic 'FilterObservation', 'StackedJiminyEnv' wrappers. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770) ([gym/common] Fix filtering and normalization wrappers. #776)
• [gym/common] Improve 'render_mode' support.
• [gym/zoo] Cleanup and speedup toy model environments. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770)
• [gym/rllib] Fix multi-GPU support using custom PPO ([gym] Enable multi-GPU support with PPO when mirror_mat are defined #774)
• [gym/rllib] Fix 'train' method typing and documentation. ([core] Full support of serialization for 'Robot'. #775)
• [misc] Fix partially broken 'mypy' static type checking for 'jiminy_py' module. ([gym/zoo] Various speed-up. Improve robustness of PGS contact solver to poor conditioning. #770)
• [misc] Add RL tutorial notebook.