Import Debian changes 3.36.3-0ubuntu0.20.04.4

gdm3 (3.36.3-0ubuntu0.20.04.4) focal; urgency=medium
.
  * debian/patches/ubuntu/reset-session-on-pam-error.patch:
    - Backport upstream commit to fix ending up on a black screen when pam
      session errors out. (LP: #1935818)