Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `Gemfile.lock`:
  Not a real conflict, upstream-updated dependency (redis) textually too
  close to glitch-soc-only dependecy.
  Updated redis gem like upstream did.

db/post_migrate/20210808071221_clear_orphaned_account_notes.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class ClearOrphanedAccountNotes < ActiveRecord::Migration[5.2]
+  class Account < ApplicationRecord
+    # Dummy class, to make migration possible across version changes
+  end
+
+  class AccountNote < ApplicationRecord
+    # Dummy class, to make migration possible across version changes
+    belongs_to :account
+    belongs_to :target_account, class_name: 'Account'
+  end
+
+  def up
+    AccountNote.where('NOT EXISTS (SELECT * FROM users u WHERE u.account_id = account_notes.account_id)').in_batches.delete_all
+  end
+
+  def down
+    # nothing to do
+  end
+end