estimate-disk-size: Port to Python 3
I switched to f31 for my dev container, and `cosa buildextend-metal`
failed since Python 2 wasn't installed.
This was the last Python 2 script we shipped.
-#!/usr/bin/env python
+#!/usr/bin/python3
#
# Given an OSTree commit, estimate how much disk space it will take
# Derived from ostree-releng-scripts/print-commitsize
@@ -38,7 +38,7 @@ n_regfiles = 0
blks_regfiles = 0
n_symlinks = 0
blks_symlinks = 0
-for k, v in reachable.iteritems():
+for k, v in reachable.items():
csum, objtype = k.unpack()
if objtype == OSTree.ObjectType.FILE:
[_, _, finfo, _] = r.load_file(csum, None)
