Try googleapiclient.

.github/workflows/weekly.yml

@@ -1,7 +1,7 @@
 name: Daily runs
 on:
   schedule:
-    - cron: '0 8 * * 1'  # 8am on mondays
+    - cron: '0 8 * * 1'  # 8 am on mondays
   push:
     paths:
     - '.github/workflows/weekly.yml'

crispybeefbot.py

@@ -2,9 +2,9 @@
 import json
 import os
 from email.message import EmailMessage
-
+import sys
 import requests
-from google.oauth2.credentials import Credentials
+from googleapiclient.oauth2.credentials import Credentials
 from googleapiclient.discovery import build
 
 url = "http://mensazurich.ch:8080/api/de/all/getMensaForCurrentWeek"
@@ -21,6 +21,8 @@
             if "crispy beef" in " ".join(menu["description"]).lower():
                 crispy_beefs += [(info["label"], date)]
 
+if len(crispy_beefs) == 0:
+    sys.exit()
 
 subject = f"Crispy Beef on {' and '.join(c[0] for c in crispy_beefs)}"