api: fix set typo in request packages

Reported-by: Tianling Shen <cnsztl@immortalwrt.org>
Signed-off-by: Paul Spooren <mail@aparcar.org>

Author: aparcar

asu/api.py

@@ -84,7 +84,7 @@ def validate_packages(req):
         else:
             tr.add(p)
 
-    req["packages"] = list(map(lambda x: remove_prefix(x, "+"), sorted(tr)))
+    req["packages"] = set(map(lambda x: remove_prefix(x, "+"), sorted(tr)))
 
     # store request packages temporary in Redis and create a diff
     temp = str(uuid4())