Move official repository from SVN to GIT

[strk]

As per ​https://lists.osgeo.org/pipermail/postgis-devel/2019-October/028184.html

[Sandro Santilli <strk@…>]

In 1f7138d/git:

Change references from svn-trunk to master

References #4564

[strk]

Status so far:

• SVN has been turned off
• GIT can be written to by 7 committers: ​https://git.osgeo.org/gitea/org/postgis/teams/committers
• Mirrors are automatically updated by script: ​https://trac.osgeo.org/postgis/wiki/CodeMirrors
• Wiki was updated: ​https://trac.osgeo.org/postgis/wiki/CodeRepository
• Trac integration works (can browse source, can be referenced by git commit logs, can reference git commits)
• Some in-repository docs were updated (probably more to update)

Bots should be checked for still working correctly

[strk]

I see Winnie and Debbie working fine (building on commit) so the SVN hook which was pinging them was obsoleted and we don't need to migrate it to git

[strk]

I'll call this closed. Se also ​https://trac.osgeo.org/postgis/wiki/MoveToGit