chore(deps): update module github.com/fluxcd/pkg/runtime to v0.91.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
github.com/fluxcd/pkg/runtime	v0.80.0 -> v0.91.0

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Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• If you want to rebase/retry this PR, check this box

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: go.sum

Command failed: go get -t ./...
go: module github.com/fluxcd/pkg/runtime@v0.91.0 requires go >= 1.25.0; switching to go1.25.4
go: downloading go1.25.4 (linux/amd64)
go: download go1.25.4: golang.org/toolchain@v0.0.1-go1.25.4.linux-amd64: verifying module: checksum database disabled by GOSUMDB=off