Can't test drupal/barcodes on simplytest.me

Problem / Motivation

...because bcmath is not present on simplytest.me.
I don't have control over this bcmath requirement, since it is required by a third-party package used by my module.

    - drupal/barcodes dev-2.1.x requires tecnickcom/tc-lib-barcode ^2.0 -> satisfiable by tecnickcom/tc-lib-barcode[2.0.7, ..., 2.4.3].
    - tecnickcom/tc-lib-barcode[2.0.7, ..., 2.4.3] require ext-bcmath * -> it is missing from your system. Install or enable PHP's bcmath extension.

I know there's an issue open specifically for bcmath, but that has been open for four years.
🐛 Cannot manually test Commerce due to bcmath extension Needs review

My question, what is the workaround? Is there something I can do to make my module testable on simplytest.me?

Commerce also uses bcmath, but Commerce testing seems to be supported via some special-casing ("one-click demo") on simplytest.me? Can we not just fix this for everyone?