Bump yard from 0.9.38 to 0.9.42 in /demo (#4035)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

demo/Gemfile.lock

@@ -371,7 +371,7 @@ GEM
       base64
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
-    yard (0.9.38)
+    yard (0.9.42)
     zeitwerk (2.7.5)
 
 PLATFORMS