[PT Run > Calculator] Fix unit tests on non-englisch systems

[htcfreek]

Summary of the Pull Request

Fixes a bug with incorrect interpretation of the decimal separator in the unit tests of Calculator plugin.

PR Checklist

• Closes: [Run > Calculator plugin] Unit tests: Some tests are failing on non-english systems #36566
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

Run unit tests on my system with German culture and format settings.