Fix gunicorn config for free sku (#1551)

app/backend/gunicorn.conf.py

@@ -1,4 +1,5 @@
 import multiprocessing
+import os
 
 max_requests = 1000
 max_requests_jitter = 50
@@ -9,5 +10,9 @@
 # https://learn.microsoft.com/en-us/troubleshoot/azure/app-service/web-apps-performance-faqs#why-does-my-request-time-out-after-230-seconds
 
 num_cpus = multiprocessing.cpu_count()
-workers = (num_cpus * 2) + 1
+if os.getenv("WEBSITE_SKU") == "LinuxFree":
+    # Free tier reports 2 CPUs but can't handle multiple workers
+    workers = 1
+else:
+    workers = (num_cpus * 2) + 1
 worker_class = "uvicorn.workers.UvicornWorker"