[ruby/logger] Update logger.gemspec

https://github.com/ruby/logger/commit/1335a71d98

lib/logger.gemspec

@@ -1,7 +1,7 @@
 begin
-  require File.expand_path("../lib/logger/version", __FILE__)
-rescue LoadError
-  require File.expand_path("../logger/version", __FILE__)
+  require_relative "lib/logger/version"
+rescue LoadError # Fallback to load version file in ruby core repository
+  require_relative "logger/version"
 end
 
 Gem::Specification.new do |spec|
@@ -19,7 +19,7 @@ Gem::Specification.new do |spec|
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
-  
+
   spec.required_ruby_version = ">= 2.3.0"
 
   spec.add_development_dependency "bundler", ">= 0"