correct decoding of 12 UTC timestamp

[akrherz]

No description provided.

[codecov]

Codecov Report

Merging #627 (a56241b) into main (0364e69) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #627   +/-   ##
=======================================
  Coverage   96.67%   96.67%           
=======================================
  Files          78       78           
  Lines        9256     9256           
=======================================
  Hits         8948     8948           
  Misses        308      308           

Impacted Files	Coverage Δ
src/pyiem/nws/product.py	98.59% <100.00%> (ø)

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