Add support for update-ref action

[MitMaro]

Closes #750

[coveralls]

Pull Request Test Coverage Report for Build 3497290542

• 22 of 31 (70.97%) changed or added relevant lines in 9 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 94.286%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/display/src/lib.rs	5	6	83.33%
src/todo_file/src/line.rs	6	7	85.71%
src/todo_file/src/search.rs	0	7	0.0%

Totals
Change from base Build 3497129059:	-0.1%
Covered Lines:	4389
Relevant Lines:	4655

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💛 - Coveralls

[forivall]

Sorry that I wasnt able to get to this one. Life happened. But anyways, looking at the change for this does give me a good hint of all the things I would need to touch to get the other feature requests working though.