[Downloader] Cog update fails if any cog fails to install a requirement

### What Red version are you using?

3.4.16

### Cog name

Downloader

### Command name

cog update

### What did you expect to happen?

Skip the cogs that can't be updated and update the ones it can.

### What actually happened?

One (or more) of the cogs failed to update a requirement, and the updating process for all of the cogs stopped entirely.

### How can we reproduce this error?


### Anything else?

Flame told me to make this issue