btrfs_stats: Upgrade to Python 3 (#1359)
btrfs_stats: Upgrade to Python 3 (#1359)

Python 2.7 will not be maintained past 2020. Therefore upgrade
`text_collector_examples/btrfs_stats.py` to Python 3.

Signed-off-by: Benjamin Drung <86a6db991ec5c1a96f98c92b98df9d547d7c8c84@cloud.ionos.com>
derekmarcotte/node_exporter,prometheus/node_exporter,prometheus/node_exporter,prometheus/node_exporter,siavashs/node_exporter,siavashs/node_exporter,derekmarcotte/node_exporter,derekmarcotte/node_exporter,siavashs/node_exporter,siavashs/node_exporter,derekmarcotte/node_exporter