Update structopt requirement from 0.2.0 to 0.3.22

[dependabot-preview]

Updates the requirements on structopt to permit the latest version.

Changelog

Sourced from structopt's changelog.

v0.3.22 (2021-07-04)

• Add support for generics in derive

v0.3.21 (2020-11-30)

• Fixed another breakage when the struct is placed inside a macro_rules! macro.

v0.3.20 (2020-10-12)

• Fixed a breakage when the struct is placed inside a macro_rules! macro.

v0.3.19 (2020-10-08)

• Added StructOpt::from_args_safe as a shortcut for StructOpt::from_iter_safe(std::env::args_os()).
• Some links in documentation have been corrected.

v0.3.18 (2020-09-23)

• Unsafe code has been forbidden. This makes cargo geiger list structopt as "safe". Maybe it will help somebody trying to locate a bug in their dependency tree.

v0.3.17 (2020-08-25)

• Fixed a breakage with resent rustc versions due to quote_spanned misuse.

v0.3.16 (2020-08-05)

• Added the new example.
• Allow #[structopt(flatten)] fields to have doc comments. The comments are ignored.
• The paw crate is now being reexported when paw feature is enabled, see [#407](https://github.com/TeXitoi/structopt/issues/407).

v0.3.15 (2020-06-16)

• Minor documentation improvements.
• Fixed a latent bug, courtesy of @​Aaron1011.

v0.3.14 (2020-04-22)

• Minor documentation improvements.

v0.3.13 (2020-04-9)

• Bump proc-macro-error to 1.0.

... (truncated)

Commits

• 004cfc2 v0.3.22
• 4bdde69 add basic support for generic structs and enums (#483)
• d16cfd2 fix clippy
• 8161b15 Add an example using strum
• 3848d5b Fix explanation on optional string list argument
• 8bda3b6 v0.3.21
• df5c7c9 Adjust .stderr files
• 399265f cargo fmt
• 583eb82 Fix #447
• 6fa8d68 v0.3.20
• Additional commits viewable 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.

If all status checks pass Dependabot will automatically merge this pull request.

---

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)