Update tree-sitter-fsharp to version 0.3.1

[0.3.1] - 2026-07-01

Added

• Highlight unambiguous query { ... } custom operations as keywords ([#191]).
• Support for type definitions with multiline generics, trailing semicolons and more ([#181]).
• Tags for bare type declarations ([#179]).
• Doc comments between (** and *) are now treated as markdown for injection ([#186]).

Fixed

• Additional F# syntax feature fixes ([#188], [#189]).
• Corrected the test suite for newer tree-sitter releases: removed stale variable highlight assertions on unit () that no query captures.

Changed

• Updated tree-sitter to support ABI-15 ([#177]).
• Fixed the Fuzz scanner CI job: it now checks the real per-language scanner paths (fsharp/src/scanner.c, fsharp_signature/src/scanner.c) and uses the correct fsharp_signature grammar directory.
• Dependency bumps ([#174], [#178], [#185], [#190]).