Fix github workflows.

Author: ioquatix

.github/workflows/test-external.yaml

@@ -19,9 +19,9 @@ jobs:
           - ubuntu
 
         ruby:
-          - "3.2"
           - "3.3"
           - "3.4"
+          - "4.0"
 
     steps:
     - uses: actions/checkout@v5

.github/workflows/test.yaml

@@ -52,6 +52,7 @@ jobs:
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{matrix.ruby}}
+        rubygems: latest
         bundler-cache: true
 
     - name: Run tests