Remove unsed bin directory

This folder does not seem to be used since https://github.com/composer/packagist/commit/78180ff3a21db3f9f1b73b882b29b8feb6e9a2e0#diff-b5d0ee8c97c7abd7e3fa29b9a27d1780

bin/.htaccess

@@ -1 +0,0 @@
-deny from all