style(bump): Enhance type annotations

Add mypy typing for _bump_with_regex and return type of
_version_to_regex.

Author: Kurt-von-Laven

commitizen/bump.py

@@ -2,7 +2,7 @@
 from collections import OrderedDict
 from itertools import zip_longest
 from string import Template
-from typing import List, Optional, Union
+from typing import List, Optional, Tuple, Union
 
 from packaging.version import Version
 
@@ -167,7 +167,9 @@ def update_version_in_files(
             file.write("".join(version_file))
 
 
-def _bump_with_regex(version_file_contents, current_version, new_version, regex):
+def _bump_with_regex(
+    version_file_contents: str, current_version: str, new_version: str, regex: str
+) -> Tuple[bool, str]:
     current_version_found = False
     # Bumping versions that change the string length move the offset on the file contents as finditer keeps a
     # reference to the initial string that was used and calling search many times would lead in infinite loops
@@ -190,7 +192,7 @@ def _bump_with_regex(version_file_contents, current_version, new_version, regex)
     return current_version_found, version_file_contents
 
 
-def _version_to_regex(version: str):
+def _version_to_regex(version: str) -> re.Pattern:
     clean_regex = version.replace(".", r"\.").replace("+", r"\+")
     return re.compile(f"{clean_regex}")