fix: Use Alchemy's page etag generator

The `Alchemy::Page:EtagGenerator` takes time based element
publishing into account.

Author: tvdeyen

Gemfile

@@ -18,7 +18,7 @@ gemspec
 gem "sqlite3", "~> 2.2"
 
 alchemy_branch = ENV.fetch("ALCHEMY_BRANCH", "8.1-stable")
-gem "alchemy_cms", github: "AlchemyCMS/alchemy_cms", branch: alchemy_branch
+gem "alchemy_cms", github: "AlchemyCMS/alchemy_cms", branch: "page-etag-generator"
 gem "alchemy-devise", github: "AlchemyCMS/alchemy-devise", branch: "main"
 
 gem "rubocop", require: false

app/controllers/alchemy/json_api/pages_controller.rb

@@ -125,7 +125,7 @@ def etag(pages)
       end
 
       def page_cache_key(page)
-        page.cache_key_with_version
+        Alchemy::Page::EtagGenerator.new(page).call
       end
 
       def base_page_scope