Fix CI

Bumping nokogiri to support Ruby 3.1.

Author: sobrinho

Gemfile.lock

@@ -89,15 +89,15 @@ GEM
     marcel (1.0.1)
     method_source (1.0.0)
     mini_mime (1.0.3)
-    mini_portile2 (2.5.3)
+    mini_portile2 (2.7.1)
     minitest (5.14.4)
     mocha (1.12.0)
     nio4r (2.5.7)
-    nokogiri (1.11.7)
-      mini_portile2 (~> 2.5.0)
+    nokogiri (1.13.1)
+      mini_portile2 (~> 2.7.0)
       racc (~> 1.4)
     orm_adapter (0.5.0)
-    racc (1.5.2)
+    racc (1.6.0)
     rack (2.2.3)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)