Bump OTS testing version to latest

Author: chrissimpkins

resources/scripts/ots_test.sh

@@ -7,7 +7,7 @@ cargo run -p fontc -- resources/testdata/static.designspace
 
 cd build
 
-OTS_VER=9.0.0
+OTS_VER=9.1.0
 rm -f "ots-${OTS_VER}-Linux.zip"
 rm -rf "ots-${OTS_VER}-Linux"
 curl -OL "https://github.com/khaledhosny/ots/releases/download/v${OTS_VER}/ots-${OTS_VER}-Linux.zip"