fix(frontend): upgrade my plan (QuivrHQ#2167)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/public/locales/en/monetization.json

@@ -1 +1 @@
-{ "upgrade": "Upgrade", "new": "New", "manage_plan": "Manage my plan" }
+{ "upgrade": "Upgrade my plan", "new": "New", "manage_plan": "Manage my plan" }