Add setup-julia step to FormatCheck workflow

The runic-action requires Julia to be available on the runner. On
self-hosted runners Julia may not be in PATH, causing the format
check to fail. Adding setup-julia ensures Julia is available.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: claude

.github/workflows/FormatCheck.yml

@@ -14,6 +14,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: '1'
       - uses: fredrikekre/runic-action@v1
         with:
           version: '1'