📝 Update Python Types docs, add missing 3.6 / 3.9 example (#4434)

docs/en/docs/python-types.md

@@ -252,7 +252,7 @@ The second type parameter is for the values of the `dict`:
 === "Python 3.9 and above"
 
     ```Python hl_lines="1"
-    {!> ../../../docs_src/python_types/tutorial008.py!}
+    {!> ../../../docs_src/python_types/tutorial008_py39.py!}
     ```
 
 This means:

docs_src/python_types/tutorial008.py

@@ -1,4 +1,7 @@
-def process_items(prices: dict[str, float]):
+from typing import Dict
+
+
+def process_items(prices: Dict[str, float]):
     for item_name, item_price in prices.items():
         print(item_name)
         print(item_price)

docs_src/python_types/tutorial008_py39.py

@@ -0,0 +1,4 @@
+def process_items(prices: dict[str, float]):
+    for item_name, item_price in prices.items():
+        print(item_name)
+        print(item_price)