Address PHP exception on `local:commitAndPush`

[vfalconisumo]

When running local:commitAndPush, Terminus throws an exception because commitAndPush expects to return a string, but the function actually returns a void because it lacks a return statement.

This exception breaks our CI pipeline because it throws on both successful and unsuccessful runs of commitAndPush, and suppressing the error would end up hiding legitimate errors.

[stevector]

@greg-1-anderson will review/merge assuming tests pass.

[pwtyler]

I tried to push a changelog note but only succeeded in creating a new branch instead. @vfalconisumo (or someone here who knows how to use GitHub better than me 🤦🏻 ), could you pull in the commits here to the forked branch (or just push a new log update)?

[vfalconisumo]

@pwtyler I believe I was able to pull those commits into my branch this morning. Let me know if I failed miserably though :)