Bump simplicity-hl version, update changelog

[KyrylR]

The PR is about rolling out features that were added previously, they include (copy from the CHANGELOG.md):

• Migrate from the pest parser to a new chumsky-based parser, improving parser recovery and enabling multiple parse errors to be reported in one pass #185
• simc now accepts --args <file> for parameterized contracts, and witness input is supplied explicitly via --wit <file> #200
• Expose contract ABI metadata for tooling via simc --abi, and add library accessors for parameter and witness types #201, #219
• Improve compiler diagnostics further by rejecting duplicate type-alias definitions and fixing parser recovery around angle-bracket-delimited syntax #221, #222
• Correct LSP hover/completion documentation for build_tapleaf_simplicity, unwrap_left, and unwrap_right #229, #230

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I've decided to bump a minor version because of the chumsky migration, as far as I can see, it is a breaking change

Even though we did our best to test the new parser on the contracts we are working on, there could still be some nuances. Therefore, I added a release candidate suffix to make the rollout softer

Also, guys from Simplex are blocked, as they need a new version of SimplicityHL to be published in order to publish the Simplex framework to crates.io

[KyrylR]

I also took the time to refactor the notes in the CHANGELOG for the 0.4.1 release to make them more meaningful

[Arvolear]

ACK d552c1c, tested locally.

CC

@apoelstra, could you please take a look? We really need the generate_abi_meta feature to be published to crates.io so that we can go ahead with releasing Simplex alpha.

[apoelstra]

Looks good! Heads up that while we are releasing 0.5.0-rc.0, if we make any breaking changes before the next RC, we will need to call it 0.6.0-rc.0 rather than 0.5.0-rc.1.

The reason is that Cargo is completely and utterly broken regarding the way it handles suffixes. See rust-bitcoin/rust-bitcoin#5358 (comment) for way more detail than you care to read, where we were repeatedly burned by this in rust-bitcoin until I read the cargo source and then found a bunch of WONTFIX bug reports about it.

[apoelstra]

I will try to slip #231 in as well -- it will be missing a changelog entry but I think that's ok for a rc.