[PostGIS] #5888: Add packaging status badge/links from Repology

[PostGIS]

#5888: Add packaging status badge/links from Repology
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 Reporter:  strk        |      Owner:  robe
     Type:  task        |     Status:  new
 Priority:  low         |  Milestone:  Website Management, Bots
Component:  management  |    Version:
 Keywords:              |
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 See https://repology.org/project/postgis/badges

 Would be useful to have it shown as badge in code hosters and on the wiki
 / website
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Ticket URL: <https://trac.osgeo.org/postgis/ticket/5888>
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