Change checkout ref from 'stable' to 'dev'

[hverhelst]

No description provided.

[Copilot]

Pull request overview

Updates the CI workflow’s external dependency checkout to follow the dev branch of gismo/gismo, changing which upstream code is used during CI runs.

Changes:

• Change actions/checkout of gismo/gismo from ref: stable to ref: dev.

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[Copilot]

Switching the dependency checkout from ref: stable to ref: dev makes CI depend on a potentially more volatile upstream branch. If the goal isn’t explicitly to test against gismo/gismo’s latest dev, consider pinning to a tag or commit SHA (or documenting why dev is required) to keep CI runs reproducible.

Suggested change

	ref: dev
	ref: stable

[Copilot]

actions/checkout@master tracks the action’s default branch, which can change unexpectedly and is discouraged for security/reproducibility. Pin this to a stable release (e.g., actions/checkout@v4) or a specific commit SHA instead of @master.