Update code to address deepsource errors

It complained about an else-return issue[1] and some commented-out code

Link: https://pylint.pycqa.org/en/latest/user_guide/messages/refactor/no-else-return.html [1]

isort/deprecated/finders.py

@@ -233,7 +233,6 @@ def _load_mapping() -> Optional[Dict[str, str]]:
                 import_name, _, pypi_name = line.strip().partition(":")
                 mappings[pypi_name] = import_name
             return mappings
-            # return dict(tuple(line.strip().split(":")[::-1]) for line in f)
 
     def _load_names(self) -> List[str]:
         """Return list of thirdparty modules from requirements"""

isort/settings.py

@@ -554,8 +554,7 @@ def is_supported_filetype(self, file_name: str) -> bool:
                 line = fp.readline(100)
         except OSError:
             return False
-        else:
-            return bool(_SHEBANG_RE.match(line))
+        return bool(_SHEBANG_RE.match(line))
 
     def _check_folder_git_ls_files(self, folder: str) -> Optional[Path]:
         env = {**os.environ, "LANG": "C.UTF-8"}