refactor: adjust cann variant

Signed-off-by: thxCode <thxcode0824@gmail.com>

Author: thxCode

.gitignore

@@ -3,6 +3,7 @@
 .vscode/
 .DS_Store
 *.swp
+.claude/
 
 # Python-generated files
 _version.py

gpustack_runtime/detector/ascend.py

@@ -658,5 +658,5 @@ def get_ascend_cann_variant(name: str | None) -> str | None:
     if version < 260:
         return "a3"  # 910c/a3
     if version < 270:
-        return "a5"  # 910d/a5
+        return "950"  # 950/a5
     return None