import json
newConditions = {'con1': 40, 'con2': 20, 'con3': 99, 'con4': 40, 'password':
    '1234'}
params = json.dumps(newConditions).encode('utf8')
req = urllib.request.Request(conditionsSetURL, data=params, headers={
    'content-type': 'application/json'})
response = urllib.request.urlopen(req)
Python3: запрос JSON POST БЕЗ библиотеки запросов