Promote pdureau from provisional to full front end framework manager

Problem/Motivation

The core leadership team has discussed and agreed that pdureau has done a great job during his provisional term (a bit more than a year). He has demonstrated the excellent communication skills, leadership and decision-making that we look for in the FEFM role.

We have offered a him promotion to the full FEFM role, which he accepted.

Reference for the differences between the provisional and full committer roles: https://www.drupal.org/about/core/policies/roles-and-responsibilities/di...

Proposed resolution

Remove provisional designation in MAINTAINERS.txt.