fix(deps): update rust crate syn to v2.0.64

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
syn	dependencies	patch	2.0.63 -> 2.0.64

---

Release Notes

dtolnay/syn (syn)

v2.0.64

Compare Source

• Support using ParseBuffer across catch_unwind (#​1646)
• Validate that the expression in a let-else ends in brace as required by rustc (#​1648, #​1649)
• Legalize invalid const generic arguments by wrapping in braces (#​1654, #​1655)
• Fix some expression precedence edge cases involving break and return in loop headers (#​1656)
• Always print closure bodies with a brace when the closure has an explicit return type (#​1658)
• Automatically insert necessary parentheses in ToTokens for Expr when required by expression precedence (#​1659)
• Support struct literal syntax in match guard expressions (#​1662)

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.

[github-actions]

Coverage after merging renovate/cargo into main will be

92.96%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
unfmt_macros
unfmt_macros.rs	92.17%	81.25%	93.33%	92.96%	101, 104, 106–107, 110, 143, 29–30, 305, 82, 85, 87–90, 98–99