Bump octicons from 19.25.0 to 19.28.0 in /demo (#4086)

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

Author: dependabot[bot]

demo/Gemfile.lock

@@ -252,7 +252,7 @@ GEM
       racc (~> 1.4)
     nokogiri (1.19.3-x86_64-linux-gnu)
       racc (~> 1.4)
-    octicons (19.25.0)
+    octicons (19.28.0)
     oj (3.16.10)
       bigdecimal (>= 3.0)
       ostruct (>= 0.2)