🌱 Automate the release process

[EmilienM]

What this PR does / why we need it:

• Copy the (exact same) release GH workflow from the VSphere provider.
• Makefile: release-notes -> generate-release-notes and detect what was the previous version,
  then put the release notes into a file so the GH workflow can draft a release with it.

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[EmilienM]

I tested this on my fork:

• https://github.com/EmilienM/cluster-api-provider-openstack/releases/tag/v0.11.4
• https://github.com/EmilienM/cluster-api-provider-openstack/actions/runs/12051699712

Note: once we bump CAPI to v1.9, we'll have a few changes to do in the Makefile but I'll take care of it, see how VSphere is doing it as an great example.

[EmilienM]

/cherry-pick release-0.11
/cherry-pick release-0.10

[k8s-infra-cherrypick-robot]

@EmilienM: once the present PR merges, I will cherry-pick it on top of release-0.10, release-0.11 in new PRs and assign them to you.

In response to this:

/cherry-pick release-0.11
/cherry-pick release-0.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[lentzi90]

/lgtm

[EmilienM]

I'll go ahead and approve and use that new process the next time we tag. We'll see how it works and I'll adjust if needed.
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: EmilienM

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• OWNERS [EmilienM]

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[k8s-infra-cherrypick-robot]

@EmilienM: new pull request created: #2292

In response to this:

/cherry-pick release-0.11
/cherry-pick release-0.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[k8s-infra-cherrypick-robot]

@EmilienM: new pull request created: #2293

In response to this:

/cherry-pick release-0.11
/cherry-pick release-0.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.