update api version for 3.8

Signed-off-by: Anca Iordache <[email protected]>

compose/const.py

@@ -58,7 +58,7 @@ API_VERSIONS = {
     COMPOSEFILE_V3_5: '1.30',
     COMPOSEFILE_V3_6: '1.36',
     COMPOSEFILE_V3_7: '1.38',
-    COMPOSEFILE_V3_8: '1.38',
+    COMPOSEFILE_V3_8: '1.40',
 }
 
 API_VERSION_TO_ENGINE_VERSION = {