chore(deps): update mysql docker tag to v9.6 #2768

Job	Run time
Run HSM tests	7m 26s
Run tests and lints	1m 1s
Run OIDC conformity tests	10m 10s
Run end-to-end tests (cockroach)	6m 41s
Run end-to-end tests (cockroach, --jwt)	6m 27s
Run end-to-end tests (mysql)	5m 43s
Run end-to-end tests (postgres, --jwt)	5m 23s
Run end-to-end tests (mysql, --jwt)	5m 51s
Run end-to-end tests (postgres)	5m 44s
Run end-to-end tests (memory, --jwt)	5m 41s
Run end-to-end tests (memory)	5m 33s
Build CLI docs	0s
Generate release	0s
Draft newsletter	0s
Send newsletter	-1s
Pending approval Slack notification	-1s
	1h 5m 38s

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