feat: allow customising notify url for branches

[sweatybridge]

What kind of change does this PR introduce?

feature

What is the new behavior?

Feel free to include screenshots if it includes visual changes.

Additional context

Add any other context or screenshots.

[coveralls]

Pull Request Test Coverage Report for Build 18473583231

Details

• 0 of 8 (0.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.06%) to 54.624%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/branches.go	0	8	0.0%

Files with Coverage Reduction	New Missed Lines	%
cmd/branches.go	1	0.0%
internal/gen/keys/keys.go	5	12.9%

Totals
Change from base Build 18470605567:	-0.06%
Covered Lines:	6409
Relevant Lines:	11733

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💛 - Coveralls