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

Make also minor PEP8 coding style fixes on modified imports.
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)