Update strum requirement from 0.20 to 0.21

[dependabot-preview]

Updates the requirements on strum to permit the latest version.

Changelog

Sourced from strum's changelog.

Changelog

0.20.0

• Refactors to do better error handling. Thanks @​jplatte for these changes

  • #133
  • #134
  • #135

• Adding vis(scope) to EnumDiscriminants. #137

  • This feature works best with versions of rust >= 1.34 due to a rustc parsing error in earlier versions.
  • Earlier versions can still use vis(r#pub)

• These changes should not be breaking, but the amount of code modified was significant.

• FYI about #122. The macro renames feature will be removed in early 2021. This feature was only necessary in rust 2015 because macros didn't support qualified imports so macro names could collide between crates.

0.19.4 / 0.19.5

• Updated docs

0.19.3

• Properly error on malformed strum attributes. #119
  • These types of inputs have historically been ignore silently. This may break code that is already incorrect.
• Move docs back to rust docs. #121
• Updated the docs a second time to improve discoverability.

0.19.2

• Fixes #104. PR #105

0.19.1

• Breaking Change: EnumVariantNames now properly adjusts to the to_string and serialize attributes.
• There's a regression in this release that may make strum imcompatible with other plugins if those plugins use non-rust syntax in their attributes. #104

0.19.0

• Fixed a regression using nth_back. #85
• Added repository to Cargo.toml. #90
• Correctly handle fill align in Display impls. #95
• Breaking Change: Use Associated Constant for EnumCount instead of const fn and free constant. #99 This behavior is consistent with the other derives.
• Breaking Change. default and disabled should now be written as markers instead of key value pairs.

... (truncated)

Commits

• See full diff in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

Dependabot will not automatically merge this PR because it includes an out-of-range update to a production dependency.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language
• @dependabot badge me will comment on this PR with code to add a "Dependabot enabled" badge to your readme

Additionally, you can set the following in your Dependabot dashboard:

• Update frequency (including time of day and day of week)
• Pull request limits (per update run and/or open at any time)
• Automerge options (never/patch/minor, and dev/runtime dependencies)
• Out-of-range updates (receive only lockfile updates, if desired)
• Security updates (receive only security updates, if desired)