Fix code scanning alert no. 5: Incomplete URL substring sanitization

[SugarD-x]

Fixes https://github.com/Asshat-Gaming/DummyBot/security/code-scanning/5

To fix the problem, we need to parse the URL and validate the host against a whitelist of allowed hosts. This ensures that the URL is genuinely from SoundCloud and not a malicious URL containing "soundcloud.com" in an unexpected location.

1. Parse the URL using the url module to extract the host.
2. Check if the host is exactly "soundcloud.com" or any other allowed subdomains.
3. Replace the substring check with this more secure host validation.

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