Update Ruby version in CI matrix to 4.0

Author: MatheusRich

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
     name: Ruby ${{ matrix.ruby }}
     strategy:
       matrix:
-        ruby: ['3.2', '3.3', '3.4', 'head']
+        ruby: ['3.2', '3.3', '3.4', '4.0']
 
     steps:
       - uses: actions/checkout@v4

Gemfile.lock

@@ -126,7 +126,8 @@ GEM
       net-smtp
     marcel (1.0.4)
     mini_mime (1.1.5)
-    minitest (5.25.5)
+    minitest (6.0.1)
+      prism (~> 1.5)
     net-imap (0.5.10)
       date
       net-protocol
@@ -137,11 +138,11 @@ GEM
     net-smtp (0.5.1)
       net-protocol
     nio4r (2.7.4)
-    nokogiri (1.18.10-arm64-darwin)
+    nokogiri (1.19.0-arm64-darwin)
       racc (~> 1.4)
-    nokogiri (1.18.10-x86_64-darwin)
+    nokogiri (1.19.0-x86_64-darwin)
       racc (~> 1.4)
-    nokogiri (1.18.10-x86_64-linux-gnu)
+    nokogiri (1.19.0-x86_64-linux-gnu)
       racc (~> 1.4)
     parallel (1.27.0)
     parser (3.3.9.0)
@@ -150,7 +151,7 @@ GEM
     pp (0.6.2)
       prettyprint
     prettyprint (0.2.0)
-    prism (1.4.0)
+    prism (1.9.0)
     psych (5.2.6)
       date
       stringio