fix warning about regex from pylance.

Author: prabhakk-mw

src/jupyter_matlab_kernel/magic_execution_engine.py

@@ -144,7 +144,7 @@ def get_magics_from_cell(cell_code):
             magic_dict = magic_matches.groupdict()
             params = magic_dict["params"].strip()
             if params:
-                magic_dict["params"] = re.split("\s+", params)
+                magic_dict["params"] = re.split(r"\s+", params)
                 # transform ? parameter into a help magic, such that %%file? becomes %%help file
                 if params.startswith("?"):
                     # Ignore additional parameters after the ? parameter