build(deps): bump actions/download-artifact from 4 to 6 #374

Job	Run time
code-format	35s
check_vvl	1m 56s
mingw	1m 28s
windows (amd64_x86)	28m 39s
linux (address sanitizer, release, custom_hash_map OFF )	14m 11s
linux (thread sanitizer, release, custom_hash_map ON )	4m 15s
windows (amd64)	29m 12s
linux (address sanitizer, release, custom_hash_map ON )	14m 11s
Ubuntu Backcompat	7m 31s
linux (undefined behavior sanitizer, debug)	20m 54s
	2h 2m 52s

Provide feedback