feat: add support for auto-backports

[kuisathaverat]

What does this PR do?

Enable backports with mergify for:

• 7.x branch with the label v7.13.0
• 7.12 branch with the label v7.12.0

If any conflicts the PRs are created with the label conflict in addition a comment will be added with the actions to be done in order to fix the conflicts locally and push to the branch.

Why is it important?

Mergify provides different mechanism to interact with PRs and automate certain process.

Some examples

Backports to 7.x -> elastic/apm-pipeline-library#995
Merges to master -> elastic/apm-pipeline-library#994

Issues

• There is an initiative to automate the GitHub labels creation in each obs11 repo -> [GH][LABELS] Automation apm-pipeline-library#886
• Closes Automate backporting of PRs to active branches #4881

Actions

• Ask Infra to enable the mergify app in this project.
• Agree with the team

[v1v]

:)

[jalvz]

I know that @axw approved of this, but for my understanding what is the reason for changing the backport tool? (afaik either can be automated)

[kuisathaverat]

I know that @axw approved of this, but for my understanding what is the reason for changing the backport tool? (afaik either can be automated)

the tool used for local backport does not change, you can use whatever you want. To make the automated backport we proposed mergify over the GitHub action, for maintainability reasons, and features reasons (mergify offer more than auto-merge and auto-backport and all out of the box)
More context in these two issues:

• [mergify] backport automation to 7.x, 7.12 and 7.11 beats#24608
• [Github Action] Add backport workflow beats#24576

[ghost]

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Build stats

• Build Cause: Pull request #4990 opened

• Start Time: 2021-03-24T14:35:20.528+0000

• Duration: 42 min 45 sec

• Commit: 92436c4

Test stats 🧪

Test	Results
Failed	0
Passed	6262
Skipped	120
Total	6382

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[axw]

Thanks!

[axw]

docs issue is unrelated, merging

[jalvz]

Thanks @kuisathaverat

[axw]

@Mergifyio backport 7.x

[axw]

@Mergifyio backport 7.13