[evince] snap: update to the gnome 3.38 extension to fix the build

[Sebastien Bacher <sbacher src gnome org>]

commit 4b3dc9241c9276e568d654163d28ecffe8431277
Author: Sebastien Bacher <seb128 ubuntu com>
Date:   Wed Apr 7 17:03:38 2021 +0200

    snap: update to the gnome 3.38 extension to fix the build

 build-aux/snap/snapcraft.yaml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/build-aux/snap/snapcraft.yaml b/build-aux/snap/snapcraft.yaml
index 6ffcd2f3..4255fc3f 100644
--- a/build-aux/snap/snapcraft.yaml
+++ b/build-aux/snap/snapcraft.yaml
@@ -7,7 +7,7 @@ description: |
 
 grade: stable # must be 'stable' to release into candidate/stable channels
 confinement: strict
-base: core18
+base: core20
 
 slots:
   # for GtkApplication registration
@@ -19,7 +19,7 @@ slots:
 apps:
   evince:
     command: usr/bin/evince
-    extensions: [gnome-3-34]
+    extensions: [gnome-3-38]
     plugs:
       - avahi-observe
       - cups-control
@@ -88,7 +88,7 @@ parts:
     stage-packages:
       - libarchive13
       - libpoppler-glib8
-      - libpoppler73
+      - libpoppler97
       - libnss3
       - libnspr4
     prime: