sumologic: use milliseconds since epoch for timestamps

[pcoccoli]

Fixes #1659

[codecov]

Codecov Report

Attention: Patch coverage is 98.07692% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 86.25%. Comparing base (710af9e) to head (0f57817).

Files	Patch %	Lines
...es/sumologic/stix_translation/query_constructor.py	91.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1668   +/-   ##
========================================
  Coverage    86.25%   86.25%           
========================================
  Files          586      586           
  Lines        50024    50035   +11     
========================================
+ Hits         43148    43158   +10     
- Misses        6876     6877    +1     

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[mdazam1942]

i think there's a conflict because of the previous sumo logic pr