Restore the Ruby 4.0.6 upgrade (#4845)

PR #4831 committed a stale Gemfile.lock over the newer one, taking
.ruby-version back to 3.2.3 and rolling back active_median, dalli,
parallel, rbs and selenium-webdriver. Dockerfile and
.devcontainer/Dockerfile still build on Ruby 4, so the Gemfile's version
check fails against the image.

Restores both files to what they were before that merge.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

.ruby-version

@@ -1 +1 @@
-3.2.3
+4.0.6

Gemfile.lock

@@ -75,8 +75,8 @@ GEM
     active_link_to (1.0.5)
       actionpack
       addressable
-    active_median (0.6.0)
-      activesupport (>= 7.1)
+    active_median (1.0.0)
+      activesupport (>= 7.2)
     active_record_union (1.4.0)
       activerecord (>= 6.0)
     active_utils (3.6.0)
@@ -219,7 +219,7 @@ GEM
     csv_shaper (1.4.0)
       activesupport (>= 3.0.0)
       csv
-    dalli (4.3.3)
+    dalli (5.1.0)
       logger
     database_cleaner (2.1.0)
       database_cleaner-active_record (>= 2, < 3)
@@ -469,7 +469,7 @@ GEM
     paper_trail (17.0.0)
       activerecord (>= 7.1)
       request_store (~> 1.4)
-    parallel (1.28.0)
+    parallel (2.1.0)
     parser (3.3.12.0)
       ast (~> 2.4.1)
       racc
@@ -553,7 +553,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rbs (4.1.3)
+    rbs (4.2.0)
       logger
       prism (>= 1.6.0)
       tsort
@@ -679,7 +679,7 @@ GEM
       activemodel (>= 6.1)
       hashie
     securerandom (0.4.1)
-    selenium-webdriver (4.44.0)
+    selenium-webdriver (4.49.0)
       base64 (~> 0.2)
       logger (~> 1.4)
       rexml (~> 3.2, >= 3.2.5)
@@ -870,7 +870,7 @@ DEPENDENCIES
   xmlrpc
 
 RUBY VERSION
-  ruby 3.2.3
+  ruby 4.0.6
 
 BUNDLED WITH
   4.0.7