pango: Update to version 1.51.0

pango: Update to version 1.51.0

- IPFire-3.x
- Update from version 1.50.12 to 1.51.0
- Changelog
    1.51.0
	- itemize: Improve script itemization
	- build: Check for cairo DWrite dependency
	- win32: Fix various issues and crashes
	- layout: Add a missing switch case
    1.50.14
	- Fix underline thickness in scaled contexts
    1.50.13
	- win32: Add back fallback for empty fontsets
	- win32: Improve DirectWrite support
	- Fix word segmentation for Japanese
	- Don't set backspace-deletes-char for math symbols
	- coretext: Fix a crash
	- cairo: Apply metrics hinting to underlines too
	- Treat COLRv1 fonts as color fonts

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>