Job fails when attempting to run chmod on Windows runner

[sameagen-MW]

Several places in the setup-matlab action we assume that we're using a bash shell with exec, but this will not necessarily be true for self-hosted and leads to errors if bash is not on the path.

Places where we call commands that are not guaranteed to be on path:

• script.ts - bash
• mpm.ts - chmod
• matlab.ts - chmod