Add swww wallpaper adapter

pokemonterminal/wallpaper/adapters/swww.py

@@ -0,0 +1,22 @@
+from subprocess import run
+from shutil import which
+from . import WallpaperProvider as _WProv
+
+
+class SwwwProvider(_WProv):
+    def change_wallpaper(path: str):
+        run(["swww", "img", path], check=True)
+        
+    def is_compatible() -> bool:
+        # check if swww is installed
+        if not which("swww"):
+            return False
+
+        # check if it's working (i.e. the daemon is running)
+        if run(["swww", "query"], capture_output=True).returncode != 0:
+            return False
+
+        return True
+
+    def __str__():
+        return "swww"