[Newm] Get wallpaper from cache file

.config/newm/config.py

@@ -61,8 +61,9 @@ def on_startup():
     )
 
 
+with open("{}/.cache/wallpaper".format(os.environ["HOME"])) as file:
     background = {
-    "path": os.environ["HOME"] + "/Pictures/Wallpapers/1561879941868.jpg",
+        "path": file.read().strip(),
         "anim": True,
     }