chore: bump to v0.8.0 #16347

Job	Run time
Toml Check	25s
Check typos and docs	9s
Check License Header	1m 27s
Check (windows-2022)	7m 24s
Build GreptimeDB binaries (ubuntu-20.04)	4m 14s
Check (ubuntu-20.04)	1m 41s
Clippy	3m 8s
coverage	13m 22s
Rustfmt	32s
Sqlness Test with Kafka Wal (ubuntu-20.04)	3m 3s
Unstable Fuzz Test (unstable_fuzz_create_table_standalone)	16m 11s
Fuzz Test (fuzz_create_table)	5m 12s
Sqlness Test (ubuntu-20.04)	2m 21s
Fuzz Test (fuzz_alter_table)	4m 47s
Fuzz Test (fuzz_create_database)	5m 11s
Fuzz Test (fuzz_create_logical_table)	5m 14s
Fuzz Test (fuzz_alter_logical_table)	5m 19s
Fuzz Test (fuzz_insert)	5m 20s
Fuzz Test (fuzz_insert_logical_table)	4m 52s
	1h 29m 52s

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