Remove Record.ST.new

[kl0tl]

Description of the change

There’s no way to add fields to a mutable record, this would require the ST monad to track the added fields with row indices, so Record.ST.new can only be frozen with Record.ST.freeze or Record.ST.run, which is lot less convenient than {} 😅

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Checklist:

• Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
• Linked any existing issues or proposals that this pull request should close
• Updated or added relevant documentation
• Added a test for the contribution (if applicable)

[garyb]

😄

[JordanMartinez]

Should this PR just be updated to remove the ST module completely?