Update rake for Ruby 4.0 and add 4.0 in CI

Author: eregon

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ 2.6, 2.7, '3.0', 3.1, 3.2, 3.3, 3.4, ruby-head, truffleruby ]
+        ruby: [ 2.6, 2.7, '3.0', 3.1, 3.2, 3.3, 3.4, '4.0', ruby-head, truffleruby ]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v6

Gemfile

@@ -1,4 +1,4 @@
 source 'https://rubygems.org'
 
-gem "rake", "~> 12.3"
+gem "rake"
 gem "rspec", "~> 3.0"

Gemfile.lock

@@ -2,7 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     diff-lcs (1.4.4)
-    rake (12.3.3)
+    rake (13.4.2)
     rspec (3.10.0)
       rspec-core (~> 3.10.0)
       rspec-expectations (~> 3.10.0)
@@ -22,5 +22,5 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  rake (~> 12.3)
+  rake
   rspec (~> 3.0)