build: bumped osx and OZ dependency, removed gsn dependency

[heueristik]

OpenGSN was used for meta transactions. However, we don't actively support meta txns momentarily and don't use the custom ERC2771 Context or trusted forwarder implementations from opengsn/contracts anymore. Hence, it is unused and can be removed.

Task OS-911

Checklist:

• [x] I have selected the correct base branch.
• [x] I have performed a self-review of my own code.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [x] My changes generate no new warnings.
• [x] Any dependent changes have been merged and published in downstream modules.
• [x] I ran all tests with success and extended them if necessary.
• [x] I have updated the CHANGELOG.md file in the root folder.
• [x] I have updated the DEPLOYMENT_CHECKLIST file in the root folder.
• [x] I have updated the UPDATE_CHECKLIST file in the root folder.