fix(ci): bump erlef/setup-beam SHA for ubuntu24 runner support

**hypatia-scan.yml**: bumps `erlef/setup-beam` SHA from `2f0cc07b…` to `fc68ffb9…` so `ImageOS=ubuntu24` resolves to `ubuntu-24.04` (matches the pin in hyperpolymath/hypatia upstream).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: hyperpolymath

.github/workflows/hypatia-scan.yml

@@ -31,7 +31,7 @@ jobs:
           fetch-depth: 0  # Full history for better pattern analysis
 
       - name: Setup Elixir for Hypatia scanner
-        uses: erlef/setup-beam@e6d7c94229049569db56a7ad5a540c051a010af9 # v1.18.2
+        uses: erlef/setup-beam@fc68ffb90438ef2936bbb3251622353b3dcb2f93 # v1.18.2
         with:
           elixir-version: '1.19.4'
           otp-version: '28.3'