feat: `run.sh` can now accept release version

[KristianBalaj]

Resolves https://github.com/ndmitchell/neil/issues/47

Backward compatibility of the run.sh doesn't change, it can still be run the following:

curl -sSL https://raw.github.com/ndmitchell/neil/master/misc/run.sh | sh -s -- hlint .

But now, optionally a version of the package can be specified (otherwise latest is picked):

curl -sSL https://raw.github.com/ndmitchell/neil/master/misc/run.sh | sh -s -- hlint@3.4.1 .

NOTE: When there's a minor version, that one is picked instead. I.e. if I would specify hlint@3.4 the hlint@3.4.1 would be picked

[KristianBalaj]

Now it should be ready

[ndmitchell]

Thanks! This is really cool