Update to kurbo 0.6.1

Author: cmyr

druid-shell/Cargo.toml

@@ -19,7 +19,7 @@ default-target = "x86_64-pc-windows-msvc"
 # NOTE: When changing the piet or kurbo versions, ensure that
 #       the kurbo version included in piet is compatible with the kurbo version specified here.
 piet-common = "0.1.1"
-kurbo = "0.6.0"
+kurbo = "0.6.1"
 
 log = "0.4.8"
 lazy_static = "1.4.0"