FIX python3 call in opencanaryd

[hagen-bauer-regioit]

Proposed changes

Fix python call to python3

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update

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[thinkst-az]

Thanks for the fix @hagen-bauer-regioit !