remove is_trivial type trait

[20162026]

Remove deprecate is_trivial type trait from inplace_vector to fix compiler warnings.

this PR has cherrypicked changes from #97 to fix test compilation under gcc15,
to avoid potential issues it should be merged after #97

tested with ghcr.io/bemanproject/infra-containers-gcc:latest GCC 15.2.0 C++26

[JeffGarland]

Dang, since I was the one holding up #79 with questions 🤦 . I feel really bad the ball got dropped. I'm going to just merge #79 because it's probably fine.

edit: done

[JeffGarland]

@20162026 I'd suggest updating the CI to include gcc-15 -- it's being used in many repos now

[20162026]

@20162026 I'd suggest updating the CI to include gcc-15 -- it's being used in many repos now

Current CI workflow would require major overhaul to support gcc 15 as it is using old beman container registry that has no images for 15

I guess it will (or at least should be) addressed in #103

[JeffGarland]

Current CI workflow would require major overhaul to support gcc 15 as it is using old beman container registry that has no images for 15

I guess it will (or at least should be) addressed in #103

Yes, it's not really that difficult as I understand it -- optional got converted.