added a new custom exception, and an api, to fetch direct url

src/music_kraken/utils/exception/download.py

@@ -0,0 +1,11 @@
+class DownloadException(Exception):
+    pass
+
+
+class UrlNotFoundException(DownloadException):
+    def __init__(self, url: str, *args: object) -> None:
+        self.url = url
+        super().__init__(*args)
+        
+    def __str__(self) -> str:
+        return f"Couldn't find the page of {self.url}"