No bug - Remove stale reference from a comment.

I removed the version number from osx.py in bug 1482923.

DONTBUILD, comment only.

taskcluster/scripts/misc/build-cbindgen.sh

@@ -2,7 +2,7 @@
 set -x -e -v
 
 # If you update this, make sure to update the minimum version in
-# build/moz.configure/rust.configure and python/mozboot/mozboot/osx.py as well.
+# build/moz.configure/rust.configure as well.
 CBINDGEN_VERSION=v0.6.7
 TARGET="$1"