Updated dependency versions
Fix phone validation in regform
Fix participant not linked to parent contribution

 - prevent ContributionParticipations which are both authors and speakers to
   have their link to the contribution removed when the author is removed but
   the speaker remains.
 - fixes #1596
Add script to fix missing parent contributions

Add a script to find existing `ContributionParticipation` objects with a
missing link to their parent contribution and reset the link appropriately.