CI: Fix typo in setup-macos-codesigning action

[RytoEX]

Description

Fix a typo in setup-macos-codesigning action.

Motivation and Context

It bothers me.

How Has This Been Tested?

It hasn't been tested, but this should be a straightforward change.

Types of changes

• Code cleanup (non-breaking change which makes code smaller or more readable)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.