Fix RBS::DuplicatedDeclarationError

We remove the RBS declaration of SnakyHash::VERSION from sig/snaky_hash.rbs
because it's already declared in sig/snakey_hash/version.rbs.

This duplicate declaration causes RBS::DuplicatedDeclarationError
in projects using snaky_hash.

Author: Leo Arnold

sig/snaky_hash.rbs

@@ -1,4 +1,3 @@
 module SnakyHash
-  VERSION: String
   # See the writing guide of rbs: https://github.com/ruby/rbs#guides
 end