Add missing ostruct require, fix system tests on CI #2626

Job	Run time
javascript_test	25s
test (Gemfile, 3.2)	1m 23s
lint	19s
test (Gemfile, 2.7)	1m 10s
mongodb_test (gemfiles/mongoid_6.gemfile)	1m 36s
test (gemfiles/rails_7.0.gemfile, 3.1)	1m 36s
postgres_test (gemfiles/rails_master.gemfile, 3.3, 1)	1m 35s
mongodb_test (gemfiles/mongoid_7.gemfile)	1m 32s
test (gemfiles/rails_master.gemfile, 3.2)	2m 0s
postgres_test (gemfiles/rails_7.1_postgresql.gemfile, 3.3)	1m 41s
system_tests	27s
test (gemfiles/rails_7.0.gemfile, 3.2)	1m 34s
test (gemfiles/rails_7.1.gemfile, 3.3)	1m 35s
test (gemfiles/rails_master.gemfile, 3.3, 1)	1m 46s
test (gemfiles/rails_master.gemfile, 3.3, 1, 1)	1m 50s
	20m 29s

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