Bump versions of dependencies

[liamfallon]

This PR bumps dependencies of krm-functions-sdk to their latest versions.

[Copilot]

Pull request overview

This PR updates the Go modules in krm-functions-sdk to newer dependency versions and bumps the declared Go toolchain patch version across the repo’s Go modules.

Changes:

• Bump go directive from 1.26.2 to 1.26.3 across multiple Go modules.
• Update dependency versions (notably github.com/kptdev/kpt and several k8s.io/* and github.com/go-openapi/* packages) and refresh go.sum files.
• Add a replace directive to go/get-started/go.mod (currently not effective due to version/path issues—see PR comments).

Reviewed changes

Copilot reviewed 5 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
go/kfn/go.mod	Bumps Go patch version for the kfn module.
go/get-started/go.mod	Bumps Go patch version, updates indirect deps, and adds a replace directive.
go/get-started/go.sum	Updates checksums reflecting dependency bumps (e.g., kpt, kube-openapi, added transitive deps).
go/fn/go.mod	Bumps Go patch version and updates indirect dependency versions.
go/fn/go.sum	Refreshes dependency checksums for the fn module.
go/fn/internal/test/go.mod	Bumps Go patch version and updates dependency versions for internal tests.
go/fn/internal/test/go.sum	Refreshes checksums for internal test dependencies.
go/fn/examples/go.mod	Bumps Go patch version and updates dependency versions for examples.
go/fn/examples/go.sum	Refreshes checksums for example dependencies.

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