Merge charm-hw-health:str-bytes-conversion into charm-hw-health:master

[Joe Guo]

1. decode output from subprocess.check_output to unicode str for python3.
2. rm script encoding header(us-ascii) so it defaults to utf-8.

LP: #1879603

[Xav Paice (xavpaice)]

LGTM

review: Approve

[Alvaro Uria (aluria)]

+1

review: Approve

diff --git a/src/files/ipmi/cron_ipmi_sensors.py b/src/files/ipmi/cron_ipmi_sensors.py
index a11f9fb..8ce5ee6 100644
--- a/src/files/ipmi/cron_ipmi_sensors.py
+++ b/src/files/ipmi/cron_ipmi_sensors.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: us-ascii -*-
 
 import os
 import subprocess
@@ -40,7 +39,7 @@ def gather_metrics():
     if len(sys.argv) > 1:
         cmdline.extend(sys.argv[1:])
     try:
-        output = subprocess.check_output(cmdline)
+        output = subprocess.check_output(cmdline).decode('utf8')
     except subprocess.CalledProcessError as error:
         output = error.stdout.decode(errors='ignore')
         with open(TMP_OUTPUT_FILE, 'w') as fd: