Add GitHub workflow check to only allow merging to main from dev branch

[ortk95]

Pull request checklist

• [x] Add a clear description of the change
• [ ] Add any new tests needed
• [ ] Run spell check on new text visible to user (documentation, GUI etc.)
• [ ] Check any changes to requirements.txt are reflected in setup.py
• [ ] Check code passes CI checks (run run_ci.sh or check GitHub Actions)

See CONTRIBUTING.md for more details.

[coveralls]

Pull Request Test Coverage Report for Build 6466845475

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 99.5%

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Totals
Change from base Build 6459545914:	0.0%
Covered Lines:	2759
Relevant Lines:	2773

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💛 - Coveralls