mgr/dashboard: fix constraints.txt again

mgr/dashboard: fix constraints.txt again

The previous attempt to fix this issue
(https://github.com/ceph/ceph/pull/50207) was not successful, since the
PIP syntax for compatible versions (~=) behaves differently compared to
other package management tools (e.g.: npm).

In this case, package~=x.y.z equasl to package>=x.y.z;package==x.y.*,
instead of the desired package>=x.y.z;package==x.*.

Fixes: tracker.ceph.com/issues/58827
Signed-off-by: Ernesto Puerta <epuertat@redhat.com>