respond with 200s on error cases to avoid retries for client errs

app/api/webhooks/paypal.py

@@ -121,7 +121,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     transaction_id = notification["txn_id"]
     if (
@@ -148,7 +148,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     donation_currency = notification["mc_currency"]
     if donation_currency not in ACCEPTED_CURRENCIES:
@@ -161,7 +161,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     custom_fields = dict(urllib.parse.parse_qsl(notification["custom"]))
 
@@ -177,7 +177,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     if user is None:
         logging.error(
@@ -188,7 +188,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     user_id = user["id"]
     username = user["username"]
@@ -221,7 +221,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     donation_amount = float(notification["mc_gross"])
     if donation_amount != calculated_price:
@@ -234,7 +234,7 @@ async def process_notification(
                 "request_id": x_request_id,
             },
         )
-        return Response(status_code=400)
+        return Response(status_code=200)
 
     privileges = user["privileges"]
     donor_seconds_remaining = max(user["donor_expire"], time.time()) - time.time()