Depend on Zeitwerk 2.3

Let's bump Zeitwerk in preparation for Rails 6.1.

With Zeitwerk 2.3, applications can enable reloading and eager loading
at the same time. As of this writing, Rails does not implement that
logic, but if we do we know the dependency is in place to support it.

Zeitwerk minor releases are backwards compatible, should be a seamlessly
upgrade.

Gemfile.lock

@@ -74,7 +74,7 @@ PATH
       i18n (>= 1.6, < 2)
       minitest (~> 5.1)
       tzinfo (~> 2.0)
-      zeitwerk (~> 2.2, >= 2.2.2)
+      zeitwerk (~> 2.3)
     rails (6.1.0.alpha)
       actioncable (= 6.1.0.alpha)
       actionmailbox (= 6.1.0.alpha)
@@ -530,7 +530,7 @@ GEM
     websocket-extensions (0.1.4)
     xpath (3.2.0)
       nokogiri (~> 1.8)
-    zeitwerk (2.2.2)
+    zeitwerk (2.3.0)
 
 PLATFORMS
   java

activesupport/activesupport.gemspec

@@ -37,5 +37,5 @@ Gem::Specification.new do |s|
   s.add_dependency "tzinfo",          "~> 2.0"
   s.add_dependency "minitest",        "~> 5.1"
   s.add_dependency "concurrent-ruby", "~> 1.0", ">= 1.0.2"
-  s.add_dependency "zeitwerk",        "~> 2.2", ">= 2.2.2"
+  s.add_dependency "zeitwerk",        "~> 2.3"
 end