Bug 32061: Bump snowflake version to b4f4b29a03

projects/snowflake/config

 # vim: filetype=yaml sw=2
 version: '[% c("abbrev") %]'
-git_url: https://github.com/cohosh/snowflake
-git_hash: 49a899be452a58db27ecc94223b0c527bf8d4927
+git_url: https://git.torproject.org/pluggable-transports/snowflake.git
+git_hash: b4f4b29a037fd2444423835da5999f39525f3d24
 filename: '[% project %]-[% c("version") %]-[% c("var/osname") %]-[% c("var/build_id") %].tar.gz'
 
 var: