bpo-29919: Remove unused imports found by pyflakes (#137)

Make also minor PEP8 coding style fixes on modified imports.
diff --git a/Tools/clinic/clinic.py b/Tools/clinic/clinic.py
index 55faf1e..53108b1 100755
--- a/Tools/clinic/clinic.py
+++ b/Tools/clinic/clinic.py
@@ -7,7 +7,6 @@
 
 import abc
 import ast
-import atexit
 import collections
 import contextlib
 import copy
@@ -27,7 +26,6 @@
 import textwrap
 import traceback
 import types
-import uuid
 
 from types import *
 NoneType = type(None)
diff --git a/Tools/msi/make_zip.py b/Tools/msi/make_zip.py
index 710e4a5..0034f6b 100644
--- a/Tools/msi/make_zip.py
+++ b/Tools/msi/make_zip.py
@@ -10,7 +10,7 @@
 from itertools import chain
 from pathlib import Path
 from zipfile import ZipFile, ZIP_DEFLATED
-import subprocess
+
 
 TKTCL_RE = re.compile(r'^(_?tk|tcl).+\.(pyd|dll)', re.IGNORECASE)
 DEBUG_RE = re.compile(r'_d\.(pyd|dll|exe|pdb|lib)$', re.IGNORECASE)
diff --git a/Tools/tz/zdump.py b/Tools/tz/zdump.py
index f94b483..39de0a4 100644
--- a/Tools/tz/zdump.py
+++ b/Tools/tz/zdump.py
@@ -3,7 +3,7 @@
 import struct
 from array import array
 from collections import namedtuple
-from datetime import datetime, timedelta
+from datetime import datetime
 
 ttinfo = namedtuple('ttinfo', ['tt_gmtoff', 'tt_isdst', 'tt_abbrind'])