♻️ Use __dir__, not File.expand_path '..', __FILE__

It's simpler and easier to read.

net-imap.gemspec

@@ -25,7 +25,7 @@ Gem::Specification.new do |spec|
 
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
-  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+  spec.files         = Dir.chdir(__dir__) do
     `git ls-files -z 2>/dev/null`.split("\x0")
       .grep_v(%r{^(\.git(ignore)?|\.mailmap|(\.github|bin|test|spec|benchmarks|features|rfcs)/)})
   end