Deploy documentation

[MattiSG]

Technical changes

• Update documentation deployment trigger to adapt to Switch to GitHub Actions openfisca-doc#308

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Proof that the deployment is triggered can be found on the Doc Actions log.

Details of implementation and difficulties can be found on openfisca/openfisca-doc#308 (comment).

I suggest to wait until openfisca/openfisca-doc#309 is merged to proceed with merging this PR, as it would be the ideal moment to change the ref to main rather than having an additional patch published later. The review is still relevant to have now thought, considering that the logic itself will not change.

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If this PR is merged:

• CIRCLECI_OPENFISCADOC_TOKEN secret should be erased
• CIRCLECI_V1_OPENFISCADOC_TOKEN secret should be erased

[coveralls]

coverage: 74.48%. remained the same
when pulling 005c5c6 on deploy-doc
into 46c7c7e on master.

[MattiSG]

Proven to work: this core deploy triggered this doc deploy.