mio d66ae04c68 testing/oha: increase ulimit for tests
Example errors on the edge builders:

```
---- test_json_schema stdout ----

thread 'test_json_schema' (5470) panicked at tests/tests.rs:1160:26:
called `Result::unwrap()` on an `Err` value: No file descriptors available (os error 24)

---- test_google stdout ----

thread 'test_google' (5465) panicked at src/client.rs:2391:26:
called `Result::unwrap()` on an `Err` value: Os { code: 24, kind: Uncategorized, message: "No file descriptors available" }

```
2025-12-04 18:42:21 +00:00
..