elements/components/pango.bst: update to 1.44.6

This minor release contains some bugfixes and also re-adds missing symbols which means it breaks forward compatibility and can't be merged after release.

Add track-extra because tag is outside master

Overview of changes in 1.44.6

• docs: Fix symbol indices
• Fix Thai line breaking
• Re-add symbols needed by some bindings
• Don't insert hyphens for some languages
• Fix a crash with hyphenation