Update dev env and CI to use Ruby 4.0.1 and rubygems/bundler 4.0.4

Additionally bumps rdoc from 7.0.3 to 7.1.0 to address console warnings.

Author: larouxn

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         uses: ruby/setup-ruby@675dd7ba1b06c8786a1480d89c384f5620a42647 # v1.281.0
         with:
           bundler-cache: true
-          rubygems: 3.6.2
+          rubygems: 4.0.4
       - name: Run type check
         run: bin/typecheck
       - name: Run type check with Prism parser

.ruby-version

@@ -1 +1 @@
-4.0.0
+4.0.1

Gemfile.lock

@@ -308,7 +308,8 @@ GEM
     rbs (4.0.0.dev.4)
       logger
       prism (>= 1.3.0)
-    rdoc (7.0.3)
+      tsort
+    rdoc (7.1.0)
       erb
       psych (>= 4.0.0)
       tsort
@@ -466,4 +467,4 @@ DEPENDENCIES
   xpath
 
 BUNDLED WITH
-  4.0.3
+  4.0.4