Bump pyo3 to 0.21.2

[Rigidity]

I followed my editor's deprecation warnings and the pyo3 migration guide.

[coveralls-official]

Pull Request Test Coverage Report for Build 9128930984

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 133 of 190 (70.0%) changed or added relevant lines in 24 files are covered.
• 30 unchanged lines in 6 files lost coverage.
• Overall coverage decreased (-0.09%) to 84.07%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
crates/chia-bls/src/gtelement.rs	0	1	0.0%
crates/chia-protocol/src/unfinished_block.rs	0	1	0.0%
crates/chia-protocol/src/unfinished_header_block.rs	0	1	0.0%
crates/chia-protocol/src/block_record.rs	23	25	92.0%
crates/chia-protocol/src/wallet_protocol.rs	0	2	0.0%
crates/chia-protocol/src/fullblock.rs	0	3	0.0%
crates/chia-protocol/src/header_block.rs	0	3	0.0%
crates/chia-protocol/src/spend_bundle.rs	0	3	0.0%
crates/chia-protocol/src/chia_protocol.rs	0	4	0.0%
crates/chia-protocol/src/program.rs	18	22	81.82%

Files with Coverage Reduction	New Missed Lines	%
crates/chia-protocol/src/bytes.rs	1	86.54%
crates/chia-protocol/src/wallet_protocol.rs	1	0.0%
crates/chia-protocol/src/chia_protocol.rs	2	0.0%
wheel/src/api.rs	2	77.53%
crates/chia-traits/src/int.rs	4	14.71%
crates/chia-puzzles/src/puzzles/singleton.rs	20	12.9%

Totals
Change from base Build 9085195791:	-0.09%
Covered Lines:	12027
Relevant Lines:	14306

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💛 - Coveralls