Update Matchstick-AS

[brunomenezes]

📄 Context

We use the matchstick-as library for unit testing the logic of the handler. It is good to keep up with evolution and not fall behind. Currently, the pos-subgraph and rollups-subgraph packages are using version 0.5.0.

📈 Subtasks

• Update the package.json to the new fixed version ( i.e. no ^ or ~ )
• Check the release changelog for new features that could benefit the current base code.
• Create the corresponding issue if an update requires major work.
• Make sure dependencies are updated in the lock file (yarn.lock).
• Verify whether everything is working as expected. i.e. run the tests using the new version.