change failure exit code

[emmaai]

Require a non 0 exit code to mark the failure and trigger retry. It is not a good practice to exit everything with 0.
Scenario on k8s:

• liveness probe run every 5s
• within 5s interval stats failed and exit 0
• nobody knows which ones failed which one succeeded

[codecov]

Codecov Report

Merging #27 (1ed13e8) into develop (5346762) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop      #27   +/-   ##
========================================
  Coverage    61.82%   61.82%           
========================================
  Files           20       20           
  Lines         1949     1949           
========================================
  Hits          1205     1205           
  Misses         744      744           

Impacted Files	Coverage Δ
odc/stats/_version.py	100.00% <100.00%> (ø)

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[omad]

That looks better.