add whitespace fixer to pre-commit config

Author: RasmusOrsoe

.pre-commit-config.yaml

@@ -26,4 +26,9 @@ repos:
     hooks:
     - id: mypy
       args: [--follow-imports=silent, --disallow-untyped-defs, --disallow-incomplete-defs, --disallow-untyped-calls]
-      language_version: python3
+      language_version: python3
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.6.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer