Update target platform for Alf

[abstratt]

Need to determine the minimum requirements for the Alf RI (including the Eclipse platform, Papyrus, Moka, Eclipse UML2) and update the target platform accordingly.

This is a follow up for when #78 is addressed.

[seidewitz]

The target platform was updated to use the Eclipse 2020-06 platform in v1.1.0j and Eclipse UML2 5.5. However, it is still using Moka 3.1.0, which is not compatible with the latest Moka releases. The Moka integration needs to be updated to use more recent versions of Moka.