community/netpbm: upgrade to 11.8.1
24.10.23 BJH Release 11.08.01
pcxtoppm: Fix wildly incorrect output for all multiplane
images. Broken in Netpbm 11.04 (September 2023).
pbmtoascii: fix bug: allows both -1x2 and -2x4. Always present
(pbmtoascii existed in primordial Netpbm).