fix CI: bump pixi version 0.41.4 -> 0.63.2 to match lockfile format

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sweverett

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
 
       - uses: prefix-dev/setup-pixi@v0.8.1
         with:
-          pixi-version: v0.41.4
+          pixi-version: v0.63.2
 
       - name: Lint
         run: pixi run lint