sysutils/puppet6: Fix build with rubygem-concurrent-ruby 1.2.0+

- Bump PORTREVISION for package change

Use ThreadLocalVar instead of RubyThreadLocalVar which was removed in 1.2.0.
RubyThreadLocalVar is a private class and an implementation detail.

Reference:	https://github.com/ruby-concurrency/concurrent-ruby/pull/988
		https://github.com/ruby-concurrency/concurrent-ruby/issues/986
		https://github.com/puppetlabs/puppet/commit/9182bc3dd2576f409a6d01fb5c08d392670e90a2