Updated the Change Password URL for Proton

[gracjankn]

Overall Checklist

• I agree to the project's Developer Certificate of Origin
• The top-level JSON objects are sorted alphabetically
• There are no open pull requests for the same update

for change-password-URLs.json

• There is no Well-Known URL for Changing Passwords (https://example.com/.well-known/change-password)
• The URL either makes the experience better or no worse than being directed to just the domain in a non-logged-in state

Proton has changed the domain there are using to sign in to their services.

I know that the URL says it's for Proton VPN rather than Proton Mail, but both services use shared credentials. The reason I picked a URL with VPN in the middle rather than Mail is that this URL will work regardless of what services by Proton a person uses.

It is possible to use some of the Proton services without having a Proton Mail address. In this case if you use a URL with "/mail/" rather than "/vpn/" the website prompts you to create a new Proton Mail address, instead of open the account settings.

There is also an existing, not-yet merged Pull Request by another person that reflects Proton's domain change in Shared Credentials. #521