Update cbindgen requirement from 0.20 to 0.21

[dependabot]

Updates the requirements on cbindgen to permit the latest version.

Release notes

Sourced from cbindgen's releases.

v0.21.0

• Update MSRV to 1.54.0
• Update clap to 3.1.
• Update heck to 0.4.0
• unraw identifiers
• Honor documentation_length in Cython.
• Add documentation_style to with short and full options
• Map RawFd to Int
• Respect remove_underscores config when prefixing name to enum

Changelog

Sourced from cbindgen's changelog.

0.21.0

  * Update MSRV to 1.54.0
  * Update clap to 3.1.
  * Update heck to 0.4.0
  * unraw identifiers
  * Honor documentation_length in Cython.
  * Add documentation_style to with short and full options
  * Map RawFd to Int
  * Respect remove_underscores config when prefixing name to enum

0.20.0

 * Add Builder::with_using_namespaces. ([#688](https://github.com/eqrion/cbindgen/issues/688))
 * Ignore PhantomPinned. ([#695](https://github.com/eqrion/cbindgen/issues/695))
 * Simplify Pin<T> to T. ([#697](https://github.com/eqrion/cbindgen/issues/697))
 * Update --pretty=expanded to -Zunpretty=expanded. ([#706](https://github.com/eqrion/cbindgen/issues/706))

0.19.0

 * Simplify types in generics ([#663](https://github.com/eqrion/cbindgen/issues/663))
 * Use --profile=check for macro expansion ([#671](https://github.com/eqrion/cbindgen/issues/671))
 * Use exported name to prefix enum variants ([#672](https://github.com/eqrion/cbindgen/issues/672))
 * Fix path attribute handling in inline submodules ([#679](https://github.com/eqrion/cbindgen/issues/679))
 * Fix a stack overflow with some recursive typedefs ([#680](https://github.com/eqrion/cbindgen/issues/680))

0.18.0

 * Simplify types in nested types such as pointed-to types and function signatures ([#661](https://github.com/eqrion/cbindgen/issues/661))

0.17.0

 * Add with_parse_extra_bindings to builder. ([#645](https://github.com/eqrion/cbindgen/issues/645))
 * Support NonZero and fix incorrect simplification of Option<ptr> into ptr. ([#647](https://github.com/eqrion/cbindgen/issues/647))
 * Deal with name conflicts correctly in declaration type resolution. ([#651](https://github.com/eqrion/cbindgen/issues/651))
 * Support pointers to ZSTs. ([#656](https://github.com/eqrion/cbindgen/issues/656))

0.16.0

 * Remove artificial restriction on lifetime parameters on enums ([#604](https://github.com/eqrion/cbindgen/issues/604))
 * Add an option for converting usize/isize into size_t/ptrdiff_t. ([#606](https://github.com/eqrion/cbindgen/issues/606))
 * Allow controlling the cargo profile used for expansion. ([#607](https://github.com/eqrion/cbindgen/issues/607))
 * Support wider range of expressions in enum discriminants ([#614](https://github.com/eqrion/cbindgen/issues/614))
 * Support generation of Cython bindings ([#590](https://github.com/eqrion/cbindgen/issues/590))
 * Fixed some issues with style=tag and recursive structs ([#615](https://github.com/eqrion/cbindgen/issues/615))
 * Default C style to Both (as specified in docs) ([#615](https://github.com/eqrion/cbindgen/issues/615))
 * Fix resolution of path dependencies from certain modules. ([#629](https://github.com/eqrion/cbindgen/issues/629))
 * Support inlined definitions for tuple variants with a single field in C ([#631](https://github.com/eqrion/cbindgen/issues/631))

Thanks to all the awesome contributors that contributed to this release.

... (truncated)

Commits

• b3de1dc v0.21.0
• d4e508d Update MSRV to 1.54.0
• 2f1202e Update clap to 3.1
• 293fcc5 Update heck to 0.4.0
• 88d4b99 Remove etesync from readme.
• b94318a Update docs.md
• fc4ab1c Remove wgpu-native from users.
• c407b7d Address clippy lint.
• ed8d946 unraw the identifiers
• 11228f6 Silence some dead_code warnings.
• Additional commits viewable in compare view

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[dependabot]

Superseded by #33.