Docker image still uses Python 2

[mpsijm]

First of all, thanks for the awesome work in #116, considering the EOL of Python 2 😄

However, the Docker image still seems to use Python 2, as shown below:

root@641e2610d3c4:/# cat /usr/bin/verifyproblem 
#! /usr/bin/python2
# EASY-INSTALL-ENTRY-SCRIPT: 'problemtools==1.20191126.post1','console_scripts','verifyproblem'
__requires__ = 'problemtools==1.20191126.post1'
import re
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0])
    sys.exit(
        load_entry_point('problemtools==1.20191126.post1', 'console_scripts', 'verifyproblem')()
    )

Just changing the shebang from /usr/bin/python2 to 3 did not work:

root@641e2610d3c4:/# python3 /usr/bin/verifyproblem 
Traceback (most recent call last):
  File "/usr/bin/verifyproblem", line 6, in <module>
    from pkg_resources import load_entry_point
ModuleNotFoundError: No module named 'pkg_resources'

P.S. various other scripts also still seem to use Python 2 in the shebang, like setup.py and problem2pdf.py.

[mpsijm]

Closed by #174 😄