Fix CI, bump dependencies and rust toolchain

[sethdusek]

CI tests were failing because of a bunch of reasons:

• The version of PyO3 we were using didn't support Python 3.14, which the runners have been updated to use
• Generic-array moving to a stable release and deprecating older versions (see Deprecation of GenericArray in v0.14.8 causes big problem with aes create (and probably others) fizyk20/generic-array#158)
• One of the nodes we use for testing NiPoPoW proofs started either timing out, or aggresively rate-limiting requests.

Additionally this PR moves to nextest, which should help reduce CI failures because of a few flaky tests (mostly ones that do network calls), and as an added bonus makes tests & coverage run significantly faster

[coveralls]

Pull Request Test Coverage Report for Build 19909456309

Details

• 20 of 24 (83.33%) changed or added relevant lines in 12 files are covered.
• 1614 unchanged lines in 221 files lost coverage.
• Overall coverage increased (+8.5%) to 86.947%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ergo-rest/src/api.rs	7	8	87.5%
ergotree-ir/src/source_span.rs	0	1	0.0%
ergo-rest/src/api/node.rs	2	4	50.0%

Files with Coverage Reduction	New Missed Lines	%
ergo-chain-types/src/autolykos_pow_scheme.rs	1	99.02%
ergo-chain-types/src/block_id.rs	1	57.14%
ergo-chain-types/src/json/autolykos_solution.rs	1	91.67%
ergo-lib/src/chain/json/transaction.rs	1	96.4%
ergo-p2p/src/codec.rs	1	0.0%
ergo-p2p/src/peer_database/in_memory.rs	1	95.0%
ergo-p2p/src/peer_feature.rs	1	96.49%
ergo-rest/src/api/peer_discovery_internals/non_chrome.rs	1	97.53%
ergo-rest/src/node_info.rs	1	0.0%
ergo-rest/src/peer_info.rs	1	86.11%

Totals
Change from base Build 16925157956:	8.5%
Covered Lines:	27478
Relevant Lines:	31603

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💛 - Coveralls