CI MakeCode: Use the default pxt-core and pxt-common-packages from package.json

[microbit-carlos]

For the MakeCode developer instructions they recommend to clone the repost and use the latest commit from the main branch, so the CI was installing the latest versions submitted to npm. However, the projects can be slightly out of sync and cause build problems:

• https://github.com/lancaster-university/codal-microbit-v2/actions/runs/4755748371/attempts/1

Relaying on the pxt-core and pxt-common-packages versions installed from package.json should be more stable.

[github-actions]

Build diff

Base commit: 2aa9b495804d664cc29fd021ec889bcf074b50d3
Action run: https://github.com/lancaster-university/codal-microbit-v2/actions/runs/4832943757

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[microbit-carlos]

Okay, I've re-run the CI and is still all good.
I'll merge now as this is a CI only change and if something is off I can fix it tomorrow before I go.