Suppress a warning around SLF4J

(I'm not sure where I should write this kind of discussion so I filed an issue. This issue is just a proposal for the maintainer; not a bug stuff 👍🏻)

We can see the following log when we launch the server (and there are lots of mentions in issues of this repo):

```
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
```

I propose that it should be ok if we suppress this warning by adding `slf4j-nop` into dependencies. The kotlin-language-server seems to be mainly taking advantage of `java.util.logging.Logger` as far as I know. I tried to add it on my local machine and the removal was working fine. The page in the message says the following thing as well:

> If you are responsible for packaging an application and do not care about logging, then placing slf4j-nop.jar on the class path of your application will get rid of this warning message

What do you think about that? If that seems to be ok, I would like to work on this!

No file or test is named in the issue. Locate the project's dependency declarations and the server launch or classpath entry point, then verify that the startup log no longer contains the SLF4J warning after the dependency change.

Written by the indexing model from the issue text.