feat!: Upgrade to OpenAPI v3

[michaeladler]

Description

Upgrading from Swagger to OpenAPI v3 offers numerous benefits, including enhanced specification features, better support for modern use cases, improved developer experience, access to a richer ecosystem and tooling, future-proofing our API specifications, and ensuring compliance and interoperability.

This upgrade is a breaking change because it requires using a different code generator, resulting in changes to the generated model. Users of the Go client library will need to make minor adjustments to their code.

Issues Addressed

List and link all the issues addressed by this PR.

Change Type

Please select the relevant options:

• Bug fix (non-breaking change that resolves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• I have read the CONTRIBUTING document.
• My changes adhere to the established code style, patterns, and best practices.
• I have added tests that demonstrate the effectiveness of my changes.
• I have updated the documentation accordingly (if applicable).
• I have added an entry in the CHANGELOG to document my changes (if applicable).

[codecov]

Codecov Report

Attention: Patch coverage is 82.06973% with 324 lines in your changes missing coverage. Please review.

Project coverage is 84.64%. Comparing base (8089eb9) to head (d1bd469).

Files with missing lines	Patch %	Lines
cmd/wfx/cmd/root/server_collection.go	71.78%	50 Missing and 18 partials ⚠️
api/wfx.go	83.56%	24 Missing and 24 partials ⚠️
cmd/wfxctl/flags/basecmd.go	71.32%	28 Missing and 13 partials ⚠️
cmd/wfx/cmd/config/appconfig.go	84.47%	25 Missing and 9 partials ⚠️
cmd/wfx/cmd/root/root.go	71.59%	18 Missing and 7 partials ⚠️
cmd/wfxctl/cmd/job/events/events.go	73.77%	10 Missing and 6 partials ⚠️
cmd/wfxctl/cmd/job/create/create.go	76.59%	8 Missing and 3 partials ⚠️
cmd/wfxctl/cmd/workflow/validate/validate.go	74.35%	5 Missing and 5 partials ⚠️
cmd/wfxctl/cmd/workflow/create/create.go	74.19%	5 Missing and 3 partials ⚠️
cmd/wfxctl/cmd/job/query/query.go	85.36%	3 Missing and 3 partials ⚠️
... and 16 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #197      +/-   ##
==========================================
+ Coverage   84.08%   84.64%   +0.56%     
==========================================
  Files         108       96      -12     
  Lines        3801     4058     +257     
==========================================
+ Hits         3196     3435     +239     
- Misses        387      395       +8     
- Partials      218      228      +10     

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