Change null constraints on requests table

We want `deadline` and `current_content` to have `null: false`, and our
`schema.rb` reflects this but our migrations do not - running
`rails db:migrate:reset` results in a schema diff with those columns
being nullable. This migration fixes that.

Author: young-rob

db/migrate/20260415091958_change_null_constraints_on_requests.rb

@@ -0,0 +1,8 @@
+class ChangeNullConstraintsOnRequests < ActiveRecord::Migration[8.1]
+  def change
+    change_table :requests do |t|
+      t.change_null :current_content, false
+      t.change_null :deadline, false
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.1].define(version: 2026_03_10_161215) do
+ActiveRecord::Schema[8.1].define(version: 2026_04_15_091958) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
   enable_extension "pgcrypto"