Fix target architectures in snap/snapcraft.yaml

Author: PawelLipski

snap/snapcraft.yaml

@@ -8,7 +8,11 @@ description: |
   - Automatic discovery of branch relations (`git machete discover`)
 # This software is unlikely to be used outside of desktop machines.
 # Let's limit the number of target architectures to reduce the build times.
-architectures: [ amd64, i386 ]
+architectures:
+  # See https://forum.snapcraft.io/t/how-can-i-publish-a-snap-that-can-provide-binaries-for-all-the-supported-architectures/8556/4
+  # on why not just `build-on: [ amd64, i386 ]`.
+  - build-on: amd64
+  - build-on: i386
 base: core18
 confinement: strict
 grade: stable