Fix minor deprecation warning

Author: wonder-sk

scripts/update_version.py

@@ -26,7 +26,7 @@ def replace_in_file(filepath, regex, sub):
 
 about_file = os.path.join(dir_path, os.pardir, "pygeodiff", "__about__.py")
 print("patching " + about_file)
-replace_in_file(about_file, "__version__\s=\s\".*", "__version__ = \"" + ver + "\"")
+replace_in_file(about_file, r'__version__\s=\s".*', r'__version__ = "' + ver + '"')
 
 pyproject_file = os.path.join(dir_path, os.pardir, "pyproject.toml")
 print("patching " + pyproject_file)