Upgrade to Testcontainers 1.19.6

[wilkinsona]

Supersedes #39354

[eddumelendez]

should it be backported to 3.2.x? Probably using latest version (1.19.7) So, other projects such spring-ai will benefit with new modules.

[wilkinsona]

Yes, we'll do a round of dependency upgrades across all maintained branches ahead of next week's releases.