SSL Error when sending email with SMTPLib - python-3.x

Question

I am writing a small Python program that involves sending emails to players in a game. I'm currently using SMTPlib to do so, and for the first while it worked great, however now I get this error whenever I try to run it:
Traceback (most recent call last):
File "/Users/user/Desktop/test.py", line 17, in <module>
sendEmail()
File "/Users/user/Desktop/test.py", line 11, in sendEmail
with smtplib.SMTP_SSL("smtp.gmail.com", port, context=context) as server:
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/smtplib.py", line 1034, in __init__
SMTP.__init__(self, host, port, local_hostname, timeout,
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/smtplib.py", line 253, in __init__
(code, msg) = self.connect(host, port)
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/smtplib.py", line 339, in connect
self.sock = self._get_socket(host, port, self.timeout)
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/smtplib.py", line 1041, in _get_socket
new_socket = self.context.wrap_socket(new_socket,
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ssl.py", line 500, in wrap_socket
return self.sslsocket_class._create(
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ssl.py", line 1040, in _create
self.do_handshake()
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/ssl.py", line 1309, in do_handshake
self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1122)
And the bare-bones code that throws this error:
import smtplib, ssl
def sendEmail():
port = 465 # For SSL
password = 'password'
senderEmail = 'senderEmail#email.com'
# Create a secure SSL context
context = ssl.create_default_context()
with smtplib.SMTP_SSL("smtp.gmail.com", port, context=context) as server:
server.login(senderEmail, password)
message = 'Hello world!'
server.sendmail(senderEmail, 'myEmail#email.com', message)
sendEmail()
I suspect that this error has to do with me using Python 3.9.0 instead of 3.7.6 as that is the only thing that has changed about my environment since the last time it was working, but I'm not certain about that*. What is causing this error, and what can I do to fix it?
*EDIT: I ran the same code on Python 3.7.6 in case that was the problem. Interestingly, it now gives a very similar error:
Traceback (most recent call last):
File "test.py", line 17, in <module>
sendEmail()
File "test.py", line 11, in sendEmail
with smtplib.SMTP_SSL("smtp.gmail.com", port, context=context) as server:
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py", line 1031, in __init__
source_address)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py", line 251, in __init__
(code, msg) = self.connect(host, port)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py", line 336, in connect
self.sock = self._get_socket(host, port, self.timeout)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/smtplib.py", line 1039, in _get_socket
server_hostname=self._host)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ssl.py", line 423, in wrap_socket
session=session
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ssl.py", line 870, in _create
self.do_handshake()
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ssl.py", line 1139, in do_handshake
self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1076)