[REF-3570] Remove deprecated REDIS_URL syntax (#3892)

Author: masenf

reflex/utils/prerequisites.py

@@ -325,24 +325,19 @@ def parse_redis_url() -> str | dict | None:
     """Parse the REDIS_URL in config if applicable.
 
     Returns:
-        If redis-py syntax, return the URL as it is. Otherwise, return the host/port/db as a dict.
+        If url is non-empty, return the URL as it is.
+
+    Raises:
+        ValueError: If the REDIS_URL is not a supported scheme.
     """
     config = get_config()
     if not config.redis_url:
         return None
-    if config.redis_url.startswith(("redis://", "rediss://", "unix://")):
-        return config.redis_url
-    console.deprecate(
-        feature_name="host[:port] style redis urls",
-        reason="redis-py url syntax is now being used",
-        deprecation_version="0.3.6",
-        removal_version="0.6.0",
-    )
-    redis_url, has_port, redis_port = config.redis_url.partition(":")
-    if not has_port:
-        redis_port = 6379
-    console.info(f"Using redis at {config.redis_url}")
-    return dict(host=redis_url, port=int(redis_port), db=0)
+    if not config.redis_url.startswith(("redis://", "rediss://", "unix://")):
+        raise ValueError(
+            "REDIS_URL must start with 'redis://', 'rediss://', or 'unix://'."
+        )
+    return config.redis_url
 
 
 async def get_redis_status() -> bool | None: