Update program-list.json

[xalgord]

dropbox is switched from HackerOne to Bugcrowd

Summary

< A quick summary of the associated pull request >

Quality Assurance Checklist

< Confirmation of this pull request meeting the following requirements, prior to merge >

Review Items	Y/N
Site has a publicly known bug bounty or vulnerability disclosure program	Y
Disclosure policy is publicly available	Y
Public URL	Y
Submission follows the Diodb schema

Your Twitter handle (https://twitter.com/xalgord):

[prodigysml]

Lgtm

[prodigysml]

Seems like there is a format issues @xalgord

[xalgord]

That's strange, the format is same as usual. Let me try to add contact_url in the next pull, maybe it can solve the issue.