build(snap): force pip to build all deps

This is to assess the "damage" time-wise on the building of the snap.

snap/snapcraft.yaml

@@ -80,6 +80,7 @@ parts:
         - enable-patchelf
     build-environment:
         - "CFLAGS": "$(pkg-config python-3.10 yaml-0.1 --cflags)"
+        - "PIP_NO_BINARY": ":all:"
     organize:
         bin/craftctl: libexec/rockcraft/craftctl
     override-build: |