chore(deps): bump thiserror from 1.0.69 to 2.0.21

[dependabot]

Bumps thiserror from 1.0.69 to 2.0.21.

Release notes

Sourced from thiserror's releases.

2.0.21

• Fix parsing of generic unit variants in display expressions (#459)

2.0.20

• Suppress redundant_field_names clippy lint in generated code (#454)

2.0.19

• Update to syn 3

2.0.18

• Make compatible with project-level needless_lifetimes = "forbid" (#443, thanks @​LucaCappelletti94)

2.0.17

• Use differently named __private module per patch release (#434)

2.0.16

• Add to "no-std" crates.io category (#429)

2.0.15

• Prevent Error::provide API becoming unavailable from a future new compiler lint (#427)

2.0.14

• Allow build-script cleanup failure with NFSv3 output directory to be non-fatal (#426)

2.0.13

• Documentation improvements

2.0.12

• Prevent elidable_lifetime_names pedantic clippy lint in generated impl (#413)

2.0.11

• Add feature gate to tests that use std (#409, #410, thanks @​Maytha8)

2.0.10

• Support errors containing a generic type parameter's associated type in a field (#408)

2.0.9

• Work around missing_inline_in_public_items clippy restriction being triggered in macro-generated code (#404)

2.0.8

• Improve support for macro-generated derive(Error) call sites (#399)

2.0.7

• Work around conflict with #[deny(clippy::allow_attributes)] (#397, thanks @​zertosh)

2.0.6

• Suppress deprecation warning on generated From impls (#396)

2.0.5

• Prevent deprecation warning on generated impl for deprecated type (#394)

... (truncated)

Commits

• b1827ee Release 2.0.21
• 58037b5 Merge pull request #459 from dtolnay/turbofish
• f82a0cf Keep track of nested turbofish depth
• 72ea492 Raise required compiler to Rust 1.77
• 72eea0d Resolve io_other_error clippy lint in tests
• 07f09a2 Raise required compiler to Rust 1.74
• 2715388 Update ui test suite to nightly-2026-09-22
• 5a306c7 Update ui test suite to nightly-2026-09-05
• ef9383b Update ui test suite to nightly-2026-08-22
• 8336b84 Update ui tests for version 2.0.20
• Additional commits viewable in compare view