Fix remaining YARD exception

.github/workflows/docs.yml

@@ -64,4 +64,4 @@ jobs:
 
       - name: Process rubydoc comments
         working-directory: Library/Homebrew
-        run: bundle exec yard doc --plugin sorbet --no-output #--fail-on-warning
+        run: bundle exec yard doc --plugin sorbet --no-output --fail-on-warning

Library/Homebrew/extend/ENV.rb

@@ -19,6 +19,10 @@ module Kernel
   private :superenv?
 end
 
+# @!parse
+#  # ENV is not actually a class, but this makes `YARD` happy
+#  # @see https://rubydoc.info/stdlib/core/ENV ENV core documentation
+#  class ENV; end
 module EnvActivation
   extend T::Sig