pre-commit: Add mypy hook

Signed-off-by: dann frazier <dann.frazier@chainguard.dev>

Author: dannf

.pre-commit-config.yaml

@@ -42,3 +42,7 @@ repos:
     rev: 4b5e89b4b108a6c1a000c591d334a99a80d34c7b  # frozen: 7.2.0
     hooks:
       - id: flake8
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: f40886d54c729f533f864ed6ce584e920feb0af7  # frozen: v1.15.0
+    hooks:
+      - id: mypy

pre_commit_hooks/shellcheck_run_steps.py

@@ -4,6 +4,7 @@
 import subprocess
 import tempfile
 from collections.abc import Generator
+from collections.abc import Mapping
 from collections.abc import Sequence
 from typing import Any
 from typing import NamedTuple
@@ -31,9 +32,9 @@ class Key(NamedTuple):
     unsafe: bool
 
 
-def do_shellcheck(melange_cfg):
+def do_shellcheck(melange_cfg: Mapping[str, Any]) -> None:
     if melange_cfg == {}:
-        return 0
+        return
 
     pkgs = [melange_cfg]
     pkgs.extend(melange_cfg.get("subpackages", []))