rubocop: set Lint/EmptyBlock as rubocop_todo

Library/Homebrew/.rubocop_todo.yml

@@ -22,3 +22,15 @@ Style/Documentation:
     - 'utils/popen.rb'
     - 'utils/shell.rb'
     - 'version.rb'
+
+Lint/EmptyBlock:
+  Exclude:
+    - 'dependency.rb'
+    - 'dev-cmd/extract.rb'
+    - 'test/cache_store_spec.rb'
+    - 'test/checksum_verification_spec.rb'
+    - 'test/compiler_failure_spec.rb'
+    - 'test/formula_spec.rb'
+    - 'test/formula_validation_spec.rb'
+    - 'test/pathname_spec.rb'
+    - 'test/support/fixtures/cask/Casks/*flight*.rb'