3.1.3. minimum-version attribute
Specifies the minimum Mapnik version needed to process this stylesheet.
Requires a three part version number, so 3.0.0 works but 3.0 or just 3 doesn’t. (See also https://github.com/mapnik/mapnik/issues/4369)
TODO: wiki says it prints a warning only, but at least with the Python bindings it causes a hard runtime error instead.
Example 4. Map minimum-version
<?xml version="1.0" encoding="utf-8"?>
<Map minimum-version="3.0.0">
</Map>