[Bug Report] Set avatar with an url that doesn't contain an image

### Bug Description

Executing setavatar command with URL [https://www.rmfon.pl/play,5#p](url) displays
.

### Steps to Reproduce

!setavatar [https://www.rmfon.pl/play,5#p](url)

### Expected Result

The bot to display a warning message: Invalid or missing URL

### Debug Output

```
System Properties:
java.version = 17.0.4.1
java.vm.name = OpenJDK 64-Bit Server VM
java.vm.specification.version = 17
java.runtime.name = OpenJDK Runtime Environment
java.runtime.version = 17.0.4.1+1
java.specification.version = 17
os.arch = amd64
os.name = Windows 10

JMusicBot Information:
Version = 0.3.8
Owner = 689431450508066911
Prefix = !
AltPrefix = null
MaxSeconds = 0
NPImages = false
SongInStatus = false
StayInChannel = false
UseEval = false
UpdateAlerts = true

Dependency Information:
JDA Version = 4.4.0_352
JDA-Utilities Version = 3.0.5
Lavaplayer Version = 1.3.78

Runtime Information:
Total Memory = 37
Used Memory = 14

Discord Information:
ID = 1029868760045207602
Guilds = 2
Users = 4
```

### Additional Info

_No response_

### Checklist

- [X] I have looked for information about this [within the documentation](https://jmusicbot.com/)
- [X] I have searched for similar issues [on the issues page](https://github.com/jagrosh/MusicBot/issues?q=is%3Aissue)
- [X] I am running the latest version of the bot: 

Start by locating the setavatar command and reproducing it with https://www.rmfon.pl/play,5#p. Trace how the command validates or loads the supplied URL; done means a non-image URL produces the warning “Invalid or missing URL” instead of displaying an image.

Written by the indexing model from the issue text.