Update publish-snapshots-on-merge.yml (#617)

[rpastrana]

extend action to on branch creations as well

Type of change:

• This change is a bug fix (non-breaking change which fixes an issue).
• This change is a new feature (non-breaking change which adds functionality).
• This change is a breaking change (fix or feature that will cause existing behavior to change).

Checklist:

• I have created a corresponding JIRA ticket for this submission
• My code follows the code style of this project.
  • I have applied the Eclipse code-format template provided.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly, or...
  • I have created a JIRA ticket to update the documentation.
  • Any new interfaces or exported functions are appropriately commented.
• I have read the HPCC Systems CONTRIBUTORS document (https://github.com/hpcc-systems/HPCC-Platform/wiki/Guide-for-contributors).
• The change has been fully tested:
  • This change does not cause any existing JUnits to fail.
  • I have include JUnit coverage to test this change
  • I have performed system test and covered possible regressions and side effects.
• I have given due consideration to all of the following potential concerns:
  • Scalability
  • Performance
  • Security
  • Thread-safety
  • Premature optimization
  • This change fixes the problem, not just the symptom

Testing:

[jpmcmu]

@rpastrana looks good