Try to fix HTTPS / CA issues

installer/snap/snapcraft.yaml

@@ -19,8 +19,19 @@ parts:
     source: root
   java:
     plugin: nil
-    stage-packages: [openjdk-8-jre, openjfx, jayatana]
-    after: [desktop-gtk2]
+    stage-packages:
+      - openjdk-8-jdk
+      - openjfx
+      - jayatana
+      - ca-certificates-java
+      - ca-certificates
+      - gtk2-engines-murrine
+      - hicolor-icon-theme
+    after:
+      - desktop-gtk2
   mediainfo:
     plugin: nil
-    stage-packages: [libmediainfo0v5, libchromaprint-tools, curl]
+    stage-packages:
+      - libmediainfo0v5
+      - libchromaprint-tools
+      - curl