Use local source tree for glances part

This avoids the additional time to clone the already existing repository
Signed-off-by: N林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

snap/snapcraft.yaml

@@ -35,7 +35,7 @@ plugs:
 parts:
   glances:
     plugin: python
-    source: https://github.com/nicolargo/glances.git
+    source: .
   bottle:
     plugin: python
     source: https://github.com/bottlepy/bottle.git