Upgrade Oj to v3.13.19 to fix a seg fault

What does this MR do and why?

Oj v3.13.16 introduced a new feature to obtain the line number and column in the Simple API JSON (SAJ) parser (https://github.com/ohler55/oj/pull/785), but there was a pointer type error that caused a seg fault for certain inputs. The bug was fixed in https://github.com/ohler55/oj/pull/799.

Full diff: https://my.diffend.io/gems/oj/3.13.18/3.13.19

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/369046

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