chore(deps): update darling requirement from 0.20 to 0.21

[dependabot]

Updates the requirements on darling to permit the latest version.

Release notes

Sourced from darling's releases.

v0.20.11

• Support #[darling(with = ...)] on the data field when deriving FromDeriveInput. This allows the use of simpler receiver types, such as a Vec of enum variants.
• Bump version of proc-macro2 to 1.0.86.
• Accept closures for #[darling(with = ...)] on fields in FromDeriveInput, FromMeta, FromField, etc. #309
• Add darling::util::Callable to accept a path or closure as a meta-item expression
• Add #[darling(from_word = ...)] and #[darling(from_none = ...)] to control shorthand and fallback behaviors for structs and enums deriving FromMeta #320
• Add FromMeta impl for syn::ExprRange #329

Changelog

Sourced from darling's changelog.

v0.20.11 (March 28, 2025)

• Support #[darling(with = ...)] on the data field when deriving FromDeriveInput. This allows the use of simpler receiver types, such as a Vec of enum variants.
• Bump version of proc-macro2 to 1.0.86.
• Accept closures for #[darling(with = ...)] on fields in FromDeriveInput, FromMeta, FromField, etc. #309
• Add darling::util::Callable to accept a path or closure as a meta-item expression
• Add #[darling(from_word = ...)] and #[darling(from_none = ...)] to control shorthand and fallback behaviors for structs and enums deriving FromMeta #320
• Add FromMeta impl for syn::ExprRange #329

v0.20.10 (July 9, 2024)

• Add #[allow(clippy::manual_unwrap_or_default)] to all generated impls to avoid causing clippy fails in crates using darling #296
• Properly initialize attrs magic field in derived FromAttributes impls #297

v0.20.9 (May 15, 2024)

• Allow word-form for newtype enum variants whose only field produces a value when from_none is called on their type #249
• Add FromMeta impls for the std::num::NonZero* types #288
• Fix panic in number FromMeta impls when the parsed value is too large for the receiver type #289

v0.20.8 (February 23, 2024)

• Add #[darling(with = ...)] support to attrs magic field to allow using custom receiver types for attrs #273

v0.20.7 (February 22, 2024)

• Add #[darling(flatten)] to allow forwarding unknown fields to another struct #146
• Don't suggest names of skipped fields in derived impls #268

v0.20.6 (February 14, 2024)

• Fix some missing syn invisible group handling in FromMeta impls #263
• Fix misleading error message on Error::unexpected_type so it no longer implies the type was a literal #264
• Impl FromMeta Vec of literals, e.g. LitStr #265

v0.20.5 (January 30, 2024)

• Add Flag::span inherent method, as Flag can no longer impl syn::spanned::Spanned #242

v0.20.4 (January 29, 2024)

• Accept bare paths in #[darling(default = ...)] #258
• Add FromMeta impl for PathBuf #259
• Improve FromMeta implementation for enums #260
  • Properly implement unit arms in FromMeta::from_list to provide a consistent API for heterogeneous enums that include a mix of unit, newtype and struct variants
  • Add #[darling(word)] attribute for unit enum variants (See #63 for details)

v0.20.3 (July 12, 2023)

• Add FromMeta impl for u128 and i128 #243

... (truncated)

Commits

• 82a51e0 Bump version to 0.20.11
• 61834da Impl FromMeta for syn::ExprRange (#332)
• f18d5d5 Add explicit implementations of FromMeta methods to SpannedValue and `Ove...
• a6e5f52 Move generation of from_word body for unit variants
• c8c8201 Add from_word and from_none options
• 3a848ca Extract path-or-closure to darling::util::Callable
• fa552e4 Error if attrs field is declared and forward_attrs is missing.
• af24bdf Reject extra data passed to unit enum variants
• b7a248f Fix clippy violations by removing unnecessary iifetimes
• b746a0c Accept a closure for with in lieu of a path for fields (#310)
• Additional commits viewable in compare view

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[diogomatsubara]

@dependabot rebase