Fix SyntaxWarning in objects.py

[meator]

Hi. I'm trying to package auto-cpufreq to Void Linux. Void Linux byte compiles python packages. A common annoyance that is commonly seen when byte compiling is warnings about unknown escape sequences. This exact warning happens when installing auto-cpufreq:

./usr/lib/python3.12/site-packages/auto_cpufreq/gui/objects.py:35: SyntaxWarning: invalid escape sequence '\('
  return getoutput("echo \(Snap\) $SNAP_VERSION")
./usr/lib/python3.12/site-packages/auto_cpufreq/gui/objects.py:35: SyntaxWarning: invalid escape sequence '\('
  return getoutput("echo \(Snap\) $SNAP_VERSION")

(The warning got doubled for some reason. This is probably Void's fault, not auto-cpufreq's. But it makes it twice as annoying.)

I fix this issue in this PR by using a raw string literal.

[shadeyg56]

Great, thank you!
You'll be credited as part of the next release

[meator]

Well, I have contributed a single character to the repo so far. I don't really expect any recognition for that. But thanks!