tasks.py: Drop unused imports
Drop a few imports that are not used.  These were pointed out by the
flake8 utility.
-import glob
import os
-import re
import semver
import shutil
import sys
import yaml
import tempfile
-try:
- from io import StringIO
-except ImportError:
- from StringIO import StringIO
try:
from urllib.request import urlopen
except ImportError:
