Downgrade importmap-rails to 1.2

v2.0.1 down not fire turbo:load event in test env, which causes tests to
fail.
Issue reported: https://github.com/rails/importmap-rails/issues/233

Gemfile.lock

@@ -112,7 +112,7 @@ GEM
       activesupport (>= 6.1)
     i18n (1.14.1)
       concurrent-ruby (~> 1.0)
-    importmap-rails (2.0.1)
+    importmap-rails (1.2.3)
       actionpack (>= 6.0.0)
       activesupport (>= 6.0.0)
       railties (>= 6.0.0)
@@ -255,7 +255,7 @@ DEPENDENCIES
   byebug
   capybara
   devise
-  importmap-rails
+  importmap-rails (~> 1.2.3)
   mysql2 (~> 0.5)
   puma (~> 6.0)
   rails (~> 7.1.2)