fix(deps): update rust crate rhai to v1.21.0

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
rhai (source)	dependencies	minor	1.20.1 -> 1.21.0

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Release Notes

rhaiscript/rhai (rhai)

v1.21.0

Compare Source

==============

Bug fixes

• Fixed bug in raw strings (thanks @benatkin 944).
• get_fn_metadata_list function is marked volatile.
• no-std plus sync should now build correctly (thanks stargazing-dino 947).

New Features

• It is possible to create a function pointer (FnPtr) which binds to a native Rust function or closure via FnPtr::from_dn and FnPtr::from_dyn_fn. When called in script, the embedded function will be called (thanks @makspll 952).

Enhancements

• The methods call_fn, call_native_fn, call_fn_raw and call_native_fn_raw are added to EvalContext (thanks @rawhuul 954).
• A new internals function, Engine::collect_fn_metadata, is added to collect all functions metadata. This is to facilitate better error reporting for missing functions (thanks therealprof 945).

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.58%. Comparing base (717a30f) to head (de8aff2).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1053   +/-   ##
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  Coverage   63.58%   63.58%           
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  Files          17       17           
  Lines        1071     1071           
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  Hits          681      681           
  Misses        390      390           

Flag	Coverage Δ
integration-tests	56.26% <ø> (ø)
unit-tests	37.29% <ø> (ø)

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