fix(api): resolve external knowledge API error due to excessive URL validation (#19003)
The `validators.url` method from the `validators==0.21.0` library enforces a
URL length limit of less than 90 characters, which led to failures in external
knowledge API requests for long URLs.
This PR addresses the issue by replacing `validators.url` with
`urllib.parse.urlparse`, effectively removing the restrictive URL length check.
Additionally, the unused `validators` dependency has been removed.
Fixes #18981.
Signed-off-by: kenwoodjw <blackxin55+@gmail.com>