Check-manifest pre-commit hook.

- Added check-manifest pre-commit hook.
- Implement suggestions from check-manifest.

.pre-commit-config.yaml

@@ -61,3 +61,7 @@ repos:
       - id: proselint
         types: [plain-text]
         exclude: LICENSE|requirements
+  - repo: https://github.com/mgedmin/check-manifest
+    rev: "0.39"
+    hooks:
+      - id: check-manifest

MANIFEST.in

@@ -2,3 +2,6 @@ recursive-include check_s3_bucket *.py
 exclude .pre-commit-config.yaml
 include *.rst
 include *.txt
+exclude .dockerignore
+exclude Dockerfile
+exclude Pipfile*