Undefined names: Add missing imports in monitor.py

flake8 testing of https://github.com/openai/random-network-distillation on Python 3.7.1

$ flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics

./monitor.py:144:55: F821 undefined name 'uuid'
    mon_file = "/tmp/baselines-test-%s.monitor.csv" % uuid.uuid4()
                                                      ^
./monitor.py:160:20: F821 undefined name 'pandas'
    last_logline = pandas.read_csv(f, index_col=None)
                   ^
./monitor.py:163:5: F821 undefined name 'os'
    os.remove(mon_file)    ^
3     F821 undefined name 'uuid'
3

openai / random-network-distillation

Undefined names: Add missing imports in monitor.py #2