examples: set gpus=device_count

[Borda]

What does this PR do?

use all GPUs if possible

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[codecov]

Codecov Report

Merging #638 (0be14c6) into master (f733c26) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #638   +/-   ##
=======================================
  Coverage   90.58%   90.58%           
=======================================
  Files         173      173           
  Lines        9232     9232           
=======================================
  Hits         8363     8363           
  Misses        869      869           

Flag	Coverage Δ
unittests	90.58% <ø> (ø)

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[pep8speaks]

Hello @Borda! Thanks for updating this PR.

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-08-06 12:06:48 UTC

[ethanwharris]

Looks good 😃 Why the change in semantic segmentation prediction?