Bump moto-ext to 4.2.4.post1

[viren-nadkarni]

Final bump ahead of v2.3 release

Ext Integration Tests # 2494 (seems to be a flake)

2023-09-25T10:01:44.2398121Z =========================== short test summary info ============================
2023-09-25T10:01:44.2398381Z FAILED tests/aws/services/rds/test_rds.py::TestRdsMysql::test_data_api[True]
2023-09-25T10:01:44.3346634Z �[31m= �[31m�[1m1 failed�[0m, �[32m463 passed�[0m, �[33m80 skipped�[0m, �[33m595 deselected�[0m, �[33m45 xfailed�[0m, �[33m6 xpassed�[0m, �[33m336857 warnings�[0m, �

cc: @giograno @sannya-singal

Closes #8984

[coveralls]

coverage: 83.01% (+0.07%) from 82.944% when pulling b58f6c1 on bump-moto-ext into 6802ede on master.

[github-actions]

LocalStack Community integration with Pro

       2 files         2 suites   1h 16m 37s ⏱️
2 218 tests 1 721 ✔️ 497 💤 0 ❌
2 219 runs  1 721 ✔️ 498 💤 0 ❌

Results for commit b58f6c1.