Add change password URL for lu.ma

[exh-Auster]

The "well-known URL" (https://lu.ma/.well-known/change-password) does exist, but points to a calendar:

From what I could gather, /.well-known (yes, with the dot 🙂) is the URL for the calendar, and the rest is ignored:

The option for changing the password is inside the settings page:

On signed-out access, the user is correctly redirected (via https://lu.ma/signin?next=%2Fsettings).

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