Add cleanup part to snapcraft

snap/snapcraft.yaml

@@ -222,3 +222,30 @@ parts:
     override-build: |
       cd meek-client
       go build -o $SNAPCRAFT_PART_INSTALL/bin/meek-client ./...
+
+  # This part removes all the files in this snap which already exist in
+  # connected content and base snaps. Since these files will be available
+  # at runtime from the content and base snaps, they do not need to be
+  # included in this snap itself.
+  #
+  # More info: https://forum.snapcraft.io/t/reducing-the-size-of-desktop-snaps/17280#heading--cleanup-part
+  #
+  cleanup:
+    after:  # Make this part run last; list all your other parts here
+      - onionshare-cli
+      - onionshare
+      - tor
+      - libevent
+      - obfs4
+      - snowflake-client
+      - meek-client
+    plugin: nil
+    build-snaps:  # List all content-snaps and base snaps you're using here
+      - core22
+      - go/latest/stable
+      - gnome-42-2204-sdk
+    override-prime: |
+      set -eux
+      for snap in core22 go/latest/stable gnome-42-2204-sdk; do  # List all content-snaps and base snaps you're using here
+        cd "/snap/$snap/current" && find . -type f,l -exec rm -f "$CRAFT_PRIME/{}" \;
+      done