GIT-2045: fix issue with tailing / getting appended

sanic/blueprint_group.py

@@ -170,7 +170,7 @@ def _sanitize_blueprint(self, bp: "sanic.Blueprint") -> "sanic.Blueprint":
         if self._url_prefix:
             merged_prefix = "/".join(
                 u.strip("/") for u in [self._url_prefix, bp.url_prefix or ""]
-            )
+            ).rstrip("/")
             bp.url_prefix = f"/{merged_prefix}"
         for _attr in ["version", "strict_slashes"]:
             if getattr(bp, _attr) is None: