The super lazy way to set GRAALVM_HOME

I try to keep GraalVM up to date so I never really know which version I'm running. I got tired of manually setting the GraalVM home environment variable every time so I added this to the top of my ~/.config/fish/ to make sure it's always up to date:

set -x GRAALVM_HOME (dirname (dirname (which gu)))

This means set GRAALVM_HOME to the parent directory of the directory that the GraalVM updater gu is in.