Update dependency phoenix_pubsub to v2

[renovate]

This PR contains the following updates:

Package	Update	Change
phoenix_pubsub	major	~> 1.1 -> ~> 2.0

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Configuration

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

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, 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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This PR has been generated by Mend Renovate. View repository job log here.

[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 check 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: mix.lock

Command failed: docker run --rm -v /mnt/renovate/gh/philihp/welcome2_umbrella:/mnt/renovate/gh/philihp/welcome2_umbrella -w /mnt/renovate/gh/philihp/welcome2_umbrella renovate/elixir mix deps.update phoenix_pubsub
** (Mix) Hex dependency resolution failed, change the version requirements of your dependencies or unlock them (by using mix deps.update or mix deps.unlock). If you are unable to resolve the conflicts you can try overriding with {:dependency, "~> 1.0", override: true}

[renovate]

Edited/Blocked Notification

Renovate will not automatically rebase this PR, because it does not recognize the last commit author and assumes somebody else may have edited the PR.

You can manually request rebase by checking the rebase/retry box above.

⚠️ Warning: custom changes will be lost.