Publish: don't push changes to repo if PR is open

[mtojek]

This PR modifies the publishing procedure:

• don't push changes to repo if PR is open

Spotted in: elastic/integrations#815

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: Pull request #309 opened

• Start Time: 2021-04-01T13:47:59.335+0000

• Duration: 43 min 43 sec

• Commit: 85a851d

Test stats 🧪

Test	Results
Failed	0
Passed	316
Skipped	1
Total	317

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[mtojek]

self-approved