Add EOF and trailing whitespace fixer to pre-commit config (#2330)

.pre-commit-config.yaml

@@ -28,3 +28,9 @@ repos:
     rev: v2.2.1
     hooks:
       - id: prettier
+
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.0.1
+    hooks:
+      - id: end-of-file-fixer
+      - id: trailing-whitespace

src/black/py.typed

@@ -1 +0,0 @@
-

tests/test.toml

@@ -7,4 +7,3 @@ line-length = 79
 target-version = ["py36", "py37", "py38"]
 exclude='\.pyi?$'
 include='\.py?$'
-