This would have caught the bug #11438 introduced in #11217 and fixed in #11439.

Since e81fa926, Synapse depends on
the use_float flag which has been introduced in ijson 3.1 and
is not available in 3.0. This is known to cause runtime errors
with send_join.

Signed-off-by: Daniel Molkentin <danimo@infra.run>

Co-authored-by: Daniel Molkentin <danimo@infra.run>