feat: Integrate GolangCi linter

[SVilgelm]

• Add UnsupportedVersionError type for clearer OpenAPI version errors
• Refactor OpenAPI version validation to use the new error type
• Add //nolint directive to validation error creation to suppress err113 linter
• Update test helpers in components_test.go to accept testing.TB and call tb.Helper()
• Remove trailing blank line in operation tag validation for consistency
• Update go.mod to require Go 1.22
• Simplify Contact.validateSpec by ignoring validator parameter
• Minor cleanup in RefOrSpec switch case ordering and imports

[Copilot]

Pull Request Overview

This PR integrates GolangCI-Lint and refactors OpenAPI validation and test helpers:

• Introduce UnsupportedVersionError for clearer version errors and update validateSpec
• Suppress unused‐parameter warnings in many validateSpec methods
• Update component tests to use testing.TB/tb.Helper() and bump Go to 1.22

Reviewed Changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
security-requirement.go	Suppress unused path param in validateSpec
schema.go	Fix spelling, simplify type check, adjust loop over fields
responses.go	Simplify regex using \d
ref.go	Introduce SpecNotFoundError and replace fmt.Errorf calls
parameter.go	Refactor name checks to switch, early exit on missing schema
operation.go	Remove trailing blank line in tag validation
openapi.go	Add UnsupportedVersionError and use it in version check
license.go	Drop unused validator param
external-docs.go	Drop unused validator param
extensions.go	Add UnsupportedSpecTypeError, tighten extension loop
example.go	Drop unused validator param
contact.go	Drop unused validator param
components_test.go	Change creators to accept testing.TB, call tb.Helper()
components.go	Simplify component name regex
callback.go	Return accumulated errors instead of nil in validateSpec
go.mod	Update Go version to 1.22
.golangci.yml	Add/configure GolangCI-Lint
.github/workflows/code.yaml	Run GolangCI-Lint action, remove manual gofmt/go vet steps

Comments suppressed due to low confidence (1)

schema.go:356

• The loop uses range n where n is an integer, which is invalid. It should be written as for i := 0; i < n; i++ { to iterate over the struct fields correctly.

for i := range n {