scripts: convert to python3

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I5ac0c1ac6f5420ec9763419223e651c3f887afe6
diff --git a/scripts/fru_gen.py b/scripts/fru_gen.py
index 2771498..5241f2f 100755
--- a/scripts/fru_gen.py
+++ b/scripts/fru_gen.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import os
 import sys
@@ -43,7 +43,7 @@
 
     parser.add_argument(
         'command', metavar='COMMAND', type=str,
-        choices=valid_commands.keys(),
+        choices=list(valid_commands.keys()),
         help='Command to run.')
 
     args = parser.parse_args()