Update 'create-pull-request' GitHub Action to v4

[felladrin]

Description

Update 'create-pull-request' GitHub Action to v4.
Because team-reviewers is not being set when using v3 (see the latest PR created with that template).

Related Issue(s)

None.

How to test

It has already been tested: see this PR created from this template that uses v4.

Release Notes

NONE

Documentation

None.

Werft options:

• /werft with-preview

[felladrin]

Unfortunately, I've just noticed the team-reviewer property wasn't working for that other PR.
It has actually set the reviewer based on the file changed, which belongs to the IDE team.

So I've checked the issues from the GitHub Action and found this:

• Use of team-reviewers results in: "Could not resolve to a node with the global id of..." error peter-evans/create-pull-request#155 (comment)

Maybe we can reuse this token from Robo Quat:

• gitpod/.github/workflows/changelog.yml

  Line 32 in 864214b

  TOKEN: ${{ secrets.ROBOQUAT_AUTOMATIC_CHANGELOG }}

Or we create a new one.