github: downgrade upload-artifact to v3 #417

Job	Run time
generate_target_matrix	8s
build_firmware (ath79-generic)	1h 19m 50s
build_firmware (ath79-mikrotik)	1h 16m 18s
build_firmware (ath79-nand)	1h 14m 52s
build_firmware (bcm27xx-bcm2708)	1h 6m 53s
build_firmware (bcm27xx-bcm2709)	1h 16m 32s
build_firmware (bcm27xx-bcm2710)	1h 21m 3s
build_firmware (bcm27xx-bcm2711)	1h 20m 42s
build_firmware (ipq40xx-generic)	1h 15m 30s
build_firmware (ipq40xx-mikrotik)	1h 12m 51s
build_firmware (ipq806x-generic)	1h 13m 59s
build_firmware (lantiq-xrx200)	1h 18m 41s
build_firmware (lantiq-xway)	1h 17m 28s
build_firmware (mediatek-mt7622)	1h 18m 57s
build_firmware (mpc85xx-p1010)	1h 11m 40s
build_firmware (mpc85xx-p1020)	1h 14m 45s
build_firmware (mvebu-cortexa9)	1h 13m 43s
build_firmware (ramips-mt7620)	1h 13m 4s
build_firmware (ramips-mt7621)	1h 18m 16s
build_firmware (ramips-mt76x8)	1h 13m 53s
build_firmware (realtek-rtl838x)	1h 2m 6s
build_firmware (rockchip-armv8)	1h 19m 11s
build_firmware (sunxi-cortexa7)	1h 8m 24s
build_firmware (x86-64)	1h 29m 11s
build_firmware (x86-generic)	1h 19m 57s
build_firmware (x86-geode)	1h 15m 34s
build_firmware (x86-legacy)	1h 19m 19s
create_release	0s
	1d 8h 52m 47s

Provide feedback