utils: specify type of parameter name in enc_spn

Related: OS#4963
Change-Id: I43a1e68afe9e756346bc0cfe8bda4ac665ac6c54
diff --git a/pySim/utils.py b/pySim/utils.py
index e268e42..c5075ed 100644
--- a/pySim/utils.py
+++ b/pySim/utils.py
@@ -174,7 +174,7 @@
 	name = h2s(ef[2:])
 	return (name, hplmn_disp, oplmn_disp)
 
-def enc_spn(name, hplmn_disp=False, oplmn_disp=False):
+def enc_spn(name:str, hplmn_disp=False, oplmn_disp=False):
 	byte1 = 0x00
 	if hplmn_disp: byte1 = byte1|0x01
 	if oplmn_disp: byte1 = byte1|0x02