fix(frontend): scroll modal payment (#2675)

# 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/lib/components/ui/Modal/Modal.module.scss

@@ -25,6 +25,7 @@
     max-width: 90vw;
     width: 35vw;
     height: 80vh;
+    overflow: auto;
 
     &.auto {
       height: auto;