Change PostgreSQL version check to check for PostgreSQL 10+

lib/tasks/db.rake

@@ -17,7 +17,7 @@ namespace :db do
 
   task :pre_migration_check do
     version = ActiveRecord::Base.connection.select_one("SELECT current_setting('server_version_num') AS v")['v'].to_i
-    abort 'This version of Mastodon requires PostgreSQL 9.5 or newer. Please update PostgreSQL before updating Mastodon' if version < 90_500
+    abort 'This version of Mastodon requires PostgreSQL 10.0 or newer. Please update PostgreSQL before updating Mastodon' if version < 100_000
   end
 
   Rake::Task['db:migrate'].enhance(['db:pre_migration_check'])