[DPE-3216] Bump workflow version for CI to version 8 #1130

Job	Run time
Lint	13s
Unit tests	2m 28s
Check libraries	35s
Build charms / Get workflow version / Get workflow version	3s
Build charms / Collect charms	15s
Build charms / Build mongodb charm \| base #0	1m 36s
Build charms / Build legacy-application charm \| base #0	1m 25s
Build charms / Build application charm \| base #0	1m 14s
charm-integration	10m 46s
ha-integration	52m 12s
relation-integration	17m 59s
legacy-integration	3m 11s
tls-integration	20m 39s
backup-integration	58m 24s
metric-integration	18m 35s
sharding-integration	53m 20s
sharding-relation-integration	13m 8s
	4h 16m 3s

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