Rephrase the error to more generically refer to the 'executable', whi…

…ch may not be Python. Ref #629.

keyring/backends/macOS/api.py

@@ -110,7 +110,7 @@ def raise_for_status(cls, status):
             raise SecAuthFailure(
                 status,
                 "Security Auth Failure: make sure "
-                "python is signed with codesign util",
+                "executable is signed with codesign util",
             )
         raise cls(status, "Unknown Error")