Fix Py3 compatability issue

[s0undt3ch]

What does this PR do?

See title.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@4977f17). Click here to learn what that means.
The diff coverage is 33.34%.

@@            Coverage Diff            @@
##             master   #55271   +/-   ##
=========================================
  Coverage          ?   38.31%           
=========================================
  Files             ?     1474           
  Lines             ?   260174           
  Branches          ?    55920           
=========================================
  Hits              ?    99652           
  Misses            ?   149401           
  Partials          ?    11121

Flag	Coverage Δ
#amazon1	100% <ø> (?)
#amazon2	100% <ø> (?)
#archlts	18.17% <33.34%> (?)
#centos6	100% <ø> (?)
#centos7	23.62% <ø> (?)
#centos8	100% <ø> (?)
#debian10	100% <ø> (?)
#debian8	100% <ø> (?)
#debian9	100% <ø> (?)
#fedora30	100% <ø> (?)
#fedora31	100% <ø> (?)
#m2crypto	100% <ø> (?)
#opensuse15	100% <ø> (?)
#proxy	23.66% <ø> (?)
#py2	18.71% <33.34%> (?)
#py3	18.55% <33.34%> (?)
#pycryptodomex	100% <ø> (?)
#runtests	18.92% <33.34%> (?)
#salt	18.92% <33.34%> (?)
#tcp	100% <ø> (?)
#tests	100% <ø> (?)
#tornado	100% <ø> (?)
#ubuntu1604	23.6% <ø> (?)
#ubuntu1804	100% <ø> (?)
#windows2016	100% <ø> (?)
#windows2019	100% <ø> (?)
#zeromq	18.92% <33.34%> (?)

Impacted Files	Coverage Δ
salt/modules/upstart_service.py	20.28% <33.34%> (ø)