You can follow "Obtaining an Access Token from a GitHub Application Webhook" (Jerrie Pelser), which itself takes from "JWT RSA & HMAC + ASP.NET Core" from Piotr Gankiewicz
Jerrie mentions as first step to convert your PEM file to XML format.
You can use an online tool or write a class
And you need your GitHub application Id:

You will find in the article the class JwtSecurityTokenHandler
used to create the JSON Web Token from the XML key.
In Django:
@api_view(['POST'])
@permission_classes([AllowAny, ])
def authenticate_user(request):
try:
email = request.data['email']
password = request.data['password']
user = User.objects.get(email=email, password=password)
if user:
try:
payload = jwt_payload_handler(user)
token = jwt.encode(payload, settings.SECRET_KEY)
user_details = {}
user_details['name'] = "%s %s" % (
user.first_name, user.last_name)
user_details['token'] = token
user_logged_in.send(sender=user.__class__,
request=request, user=user)
return Response(user_details, status=status.HTTP_200_OK)
except Exception as e:
raise e
else:
res = {
'error': 'can not authenticate with the given credentials or the account has been deactivated'}
return Response(res, status=status.HTTP_403_FORBIDDEN)
except KeyError:
res = {'error': 'please provide a email and a password'}
return Response(res)