add pragma no cover for to exclude from test coverage

Author: msamsami

src/linearboost/linear_boost.py

@@ -18,7 +18,7 @@
 from numbers import Integral, Real
 
 if sys.version_info >= (3, 11):
-    from typing import Self
+    from typing import Self  # pragma: no cover
 else:
     from typing_extensions import Self