ci: remove unsupported dependabot cooldown options

[Nikolas Evers (vintagesucks)]

https://github.com/shopware/SwagPlatformDemoData/runs/96388884564:

The property '#/updates/0/cooldown/semver-major-days' is not supported for the package ecosystem 'github-actions'.
The property '#/updates/0/cooldown/semver-minor-days' is not supported for the package ecosystem 'github-actions'.
The property '#/updates/0/cooldown/semver-patch-days' is not supported for the package ecosystem 'github-actions'.

^{https://docs.github.com/en/code-security/reference/supply-chain-security/dependabot-options-reference#configuration-of-cooldown}