Merge commit '425d77f8124a50fc033e8fb3bdf7b89a6a25f4fa' into glitch-soc/merge-upstream

Conflicts:
- `.rubocop_todo.yml`:
  Upstream regenerated this file, glitch-soc had a specific ignore.
- `README.md`:
  Upstream updated its README, but glitch-soc has a completely different one.
  Kept glitch-soc's README

app/validators/status_length_validator.rb

@@ -45,7 +45,7 @@ class StatusLengthValidator < ActiveModel::Validator
 
   def rewrite_entities(str, entities)
     entities.sort_by! { |entity| entity[:indices].first }
-    result = ''.dup
+    result = +''
 
     last_index = entities.reduce(0) do |index, entity|
       result << str[index...entity[:indices].first]