Make Solid Cache schema compatible with Rails 7.2

We are not dependending on any 8.0 features

Author: dhh

lib/generators/solid_cache/install/templates/db/cache_schema.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-ActiveRecord::Schema[8.0].define(version: 1) do
+ActiveRecord::Schema[7.2].define(version: 1) do
   create_table "solid_cache_entries", force: :cascade do |t|
     t.binary "key", limit: 1024, null: false
     t.binary "value", limit: 536870912, null: false