read csv file directly from URL / How to Fix a 403 Forbidden Error
The problem is that the url you have doesn't accept "non-browser" requests. The default header of Python requests is

'User-Agent': 'python-requests/2.13.0'


You can pass your own headers as an argument like that

from io import StringIO
import pandas as pd
import requests

headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.76 Safari/537.36'}

url="https://fineli.fi/fineli/en/elintarvikkeet/resultset.csv"
s=requests.get(url, headers= headers).text

c=pd.read_csv(StringIO(s), sep=";")
c