style: change DonationModal color

[yontank]

the same things are written in DonateModal and DonateButton, so we can simply export it instead of writing it twice.

There's another problem where
the modal is using an aqua themed color instead of white, if it's intended I apologize

[github-actions]

Preview: https://s3.amazonaws.com/noam-gaash.co.il/11996527282/open-bus/162/index.html
Preview Storybook: https://s3.amazonaws.com/noam-gaash.co.il/11996527282/open-bus/162/storybook/index.html
Test Report (if available): 'https://s3.amazonaws.com/noam-gaash.co.il/11996527282/open-bus/65bdad42fb5d62b6340585028a69ec1a42a87dcf/test-results/index.html'

[NoamGaash]

You're right, that's a good change.
Thank you!