If you just want to bypass verification, you can create a new SSLContext. By default newly created contexts use CERT_NONE.

Be careful with this as stated in section 17.3.7.2.1

When calling the SSLContext constructor directly, CERT_NONE is the default. Since it does not authenticate the other peer, it can be insecure, especially in client mode where most of time you would like to ensure the authenticity of the server you’re talking to. Therefore, when in client mode, it is highly recommended to use CERT_REQUIRED.

But if you just want it to work now for some other reason you can do the following, you'll have to import ssl as well:

input = input.replace("!web ", "")      
url = "https://domainsearch.p.mashape.com/index.php?name=" + input
req = urllib2.Request(url, headers={ 'X-Mashape-Key': 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' })
gcontext = ssl.SSLContext()  # Only for gangstars
info = urllib2.urlopen(req, context=gcontext).read()
Message.Chat.SendMessage ("" + info)

This should get round your problem but you're not really solving any of the issues, but you won't see the [SSL: CERTIFICATE_VERIFY_FAILED] because you now aren't verifying the cert!

To add to the above, if you want to know more about why you are seeing these issues you will want to have a look at PEP 476.

This PEP proposes to enable verification of X509 certificate signatures, as well as hostname verification for Python's HTTP clients by default, subject to opt-out on a per-call basis. This change would be applied to Python 2.7, Python 3.4, and Python 3.5.

There is an advised opt out which isn't dissimilar to my advice above:

import ssl

# This restores the same behavior as before.
context = ssl._create_unverified_context()
urllib.urlopen("https://no-valid-cert", context=context)

It also features a highly discouraged option via monkeypatching which you don't often see in python:

import ssl

ssl._create_default_https_context = ssl._create_unverified_context

Which overrides the default function for context creation with the function to create an unverified context.

Please note with this as stated in the PEP:

This guidance is aimed primarily at system administrators that wish to adopt newer versions of Python that implement this PEP in legacy environments that do not yet support certificate verification on HTTPS connections. For example, an administrator may opt out by adding the monkeypatch above to sitecustomize.py in their Standard Operating Environment for Python. Applications and libraries SHOULD NOT be making this change process wide (except perhaps in response to a system administrator controlled configuration setting).

If you want to read a paper on why not validating certs is bad in software you can find it here!

There is already an approved answer, but it didn't help in my case. Just sharing my solution here for whoever needs it:

1. First install certifi with pip install certifi.
2. Then run export SSL_CERT_FILE=$(python3 -m certifi).
3. (Optional) Create start.sh with contents below and run sh start.sh instead of python main.py every time in terminal:

export SSL_CERT_FILE=$(python3 -m certifi)
python main.py # replace with your module name

My answer is pretty similar to setting SSL_CERT_FILE to a path, however the difference is that it automatically detects the certificate path and sets it by itself. This makes it easier for running the module in different environments without worrying about certificate path.