Upgrade certora spec files and CI to certora-cli v6

[mmv08]

This PR updates the certora cli to the latest available v6 version. The main breaking change is that ghosts have to be marked persistent if we don't want them to be HAVOC'ed on, let's say, an external call.

[github-actions]

Pull Request Test Coverage Report for Build 7543498216

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.397%

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Totals
Change from base Build 7542362512:	0.0%
Covered Lines:	396
Relevant Lines:	404

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💛 - Coveralls

[mmv08]

I'm converting this to a draft because the update to v6 broke the ownerSignaturesAreProvidedForExecTransaction rule. Presumably, because the tool behaves non-deterministically for abi.encodePacked (or a hash of it) even for the same data. The certora team's investigating.

Example run: https://prover.certora.com/output/6575/96223f29578f4584b7e1afa6c4356ce8/?anonymousKey=b4c7ff82200f16cc7d24b33fca4948008693a3a7

[coveralls]

Pull Request Test Coverage Report for Build 7785684151

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall first build on certora/v6-spec-update at 94.397%

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Totals
Change from base Build 7609222733:	94.4%
Covered Lines:	396
Relevant Lines:	404

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💛 - Coveralls