filesystem.py: Fix type annotation of read_binary_dec()

Change-Id: I781fc0c564a318a6f9b2ec8dccf9f8865bff0e48
diff --git a/pySim/filesystem.py b/pySim/filesystem.py
index 55a7130..3eea2f4 100644
--- a/pySim/filesystem.py
+++ b/pySim/filesystem.py
@@ -966,7 +966,7 @@
             raise TypeError("Only works with TransparentEF")
         return self.card._scc.read_binary(self.selected_file.fid, length, offset)
 
-    def read_binary_dec(self) -> dict:
+    def read_binary_dec(self) -> Tuple[dict, str]:
         """Read [part of] a transparent EF binary data and decode it.
 
         Args: