urllibモジュールで実行

urllib_get_actiondefinitions.py

#!/usr/bin/python3
import urllib.request
import base64
import ssl
import json

# 自己証明書の警告を出力しないようにする
ssl._create_default_https_context = ssl._create_unverified_context

# URL/ユーザー情報
url = 'https://vROps IP or FQDN/suite-api/api/actiondefinitions'
user = 'admin'
passwd = 'change me'

base64string = base64.encodestring(('%s:%s' % (user, passwd)).encode('utf-8'))[:-1]

headers = {
    "Authorization": "Basic %s" % base64string.decode("utf-8"),
    'Content-Type': 'application/json',
    'Accept': 'application/json'
}
req = urllib.request.Request(url, headers=headers)
with urllib.request.urlopen(req) as res:
    html = res.read().decode('utf-8')
    r = json.loads(html)

print(json.dumps(r, indent=2))