Make python_server.py compatible to Python 3.7

Author: T-256

python_files/python_server.py

@@ -159,7 +159,10 @@ def get_value(self) -> str:
 
 def get_headers():
     headers = {}
-    while line := STDIN.readline().strip():
+    while True:
+        line = STDIN.readline().strip()
+        if not line:
+            break
         name, value = line.split(":", 1)
         headers[name] = value.strip()
     return headers