v7 os links incorrect

[sb2259]

with version 3.2.6, when importing OS Topo in v7 format schema, I get an error:

Post-processor error: Failed to download https://raw.githubusercontent.com/OrdnanceSurvey/OS-Master-Map-Topography/Styling/Stylesheets/Schema%20version%209/SQL/PostGIS/Array/topographicarea_createtable_array.sql

Adding /master to lines 47 (qml_base) and 56 (sql_base) in utils.py resolves this issue, as has already been done for v9 schemas further down in this module.

I suspect that line 56 should refer to Schema version 7 rather than Schema version 9. This was changed, and import worked fine for my data.