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• Please check if the PR fulfills these requirements

• The commit message are well described
• Docs have been added / updated (for features or maybe bugs which were noted). If not, please update the needed documentation here. This is not mandatory
• All changes have fully been tested

• What kind of change does this PR introduce? (Bug fix, feature, ...)

Feature

• What is the current behavior? (You can also link to an open issue here)

Currently, the used gametest framework in #562 is based on the 1.19.x branch of CC: Tweaked.

• What is the new behavior (if this is a feature change)?

Apparently some stuff has changed in the 1.20.x branch (for example support for client gametests) which this PR aims to backport to AP.

• Does this PR introduce a breaking change? (What changes might users need to make in their scripts due to this PR?)

All the old tests run without a problem