[PostGIS] #5666: Build reproducibility: timestamps in extension upgrade SQL scripts

[PostGIS]

#5666: Build reproducibility: timestamps in extension upgrade SQL scripts
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  Reporter:  James Addison  |      Owner:  pramsey
      Type:  defect         |     Status:  new
  Priority:  medium         |  Milestone:
 Component:  postgis        |    Version:  3.4.x
Resolution:                 |   Keywords:
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Comment (by James Addison):

 Please note: the patch as-written specifies an explicit format-string for
 the output date (`+%Y-%m-%d %H:%M:%S`), copied from the
 `POSTGIS_BUILD_DATE` format string
 ([https://trac.osgeo.org/postgis/browser/git/configure.ac?rev=c19ce56ca8982635026ba605f5b2fdce3622bb4a#L1273
 code ref]).

 The example SQL snippet in my description uses that format too - but in
 practice existing strings will have been formatted according to the build
 system's `date` program (`-- Built on Mon Nov 20 20:03:08 UTC 2023`, for
 example).
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5666#comment:1>
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