Fix missed action version update.

This triggers a warning and breaks the publish workflow - v4 can only
download artifacts uploaded with v4.

.github/workflows/ci_build.yml

@@ -68,7 +68,7 @@ jobs:
 
       - name: Upload Korman+Blender Bundle
         if: startsWith(github.ref, 'refs/tags')
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: korman-blender-${{ matrix.cfg.str }}
           path: build/package

korman/exporter/physics.py

@@ -300,6 +300,7 @@ class PhysicsConverter:
                     bo.name, volume
                 )
                 self._export_trimesh(bo, physical, local_space, mat)
+                return
 
             if local_space:
                 physical.pos = hsVector3(*mat.to_translation())