Upgrade gitlab.com/gitlab-org/moa to fix unmatched template expressions

What does this MR do?

As reported in #39268 (closed), a script as simple as:

test:
  script:
    - echo $

would return the error: ERROR: Job failed: failed to interpolate job inputs: parser: parsing string in template: string not terminating at 1:5.

This was caused by a bug in Moa where a bare $ was enough to trigger expression template parsing. This MR upgrades Moa to a version that requires the complete ${{ delimiter before parsing an expression.

The existing guard that only enables the expression language when inputs are supplied remains in place as an additional safety measure.

What's the best way to test this MR?

Moa's own test suite has been updated to cover this. No additional changes are needed in Runner.