test: raise default assert_receive timeout

In our CI we sometimes fail assert_receive statmenets even in retry
making CI results unreliabl'ish. The default is 100ms, now it is 1s.

See e.g: https://ci.akkoma.dev/repos/1/pipeline/504/5

test/test_helper.exs

@@ -6,6 +6,7 @@ os_exclude = if :os.type() == {:unix, :darwin}, do: [skip_on_mac: true], else: [
 
 ExUnit.start(
   capture_log: true,
+  assert_receive_timeout: 1_000,
   exclude: [:federated, :erratic] ++ os_exclude
 )