Disable major Docker tag updates in Renovate

[Copilot]

Renovate was proposing major PHP version bumps (e.g., 7.4-alpine → 8.x-alpine) via automated PRs. Added a packageRule to suppress these for Dockerfile dependencies, and reverted the bot's previously applied PHP tag updates.

Changes

• renovate.json: Add rule matching dockerfile manager with matchUpdateTypes: ["major"] and enabled: false — minor/patch updates are unaffected and still automerge.

{
  "matchManagers": ["dockerfile"],
  "matchUpdateTypes": ["major"],
  "enabled": false
}

• Reverted Dockerfiles: Restored the original PHP tags in all Dockerfiles that had been updated by the Renovate bot (5.6, 7.4, 7.4-ci, 7.4-symfony, 8.0, 8.0-ci, 8.0-symfony, 8.1-ci, 8.2-ci, 8.3-ci, 8.4-ci).

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[guillaume-sainthillier]

@copilot ok but revert the bot updates before merging

[Copilot]

@copilot ok but revert the bot updates before merging

Done in commit 5491089 — reverted all 11 Dockerfiles (5.6, 7.4, 7.4-ci, 7.4-symfony, 8.0, 8.0-ci, 8.0-symfony, 8.1-ci, 8.2-ci, 8.3-ci, 8.4-ci) back to their original PHP tags. The renovate.json rule to disable future major updates is still in place.