tests: functional: Set timeout to 3 hours
This commit alone doesn't fix the problem of our functional tests timing out. It is harmless to increase the timeout.
The maximum timeout for shared runners in Salsa is 3h according to this: https://salsa.debian.org/salsa-ci-team/pipeline/-/blob/master/README.md#set-build-timeout
Signed-off-by: Joseph Nuthalapati njoseph@riseup.net