Add task_thread_pool to benchmarks

[alugowski]

Add https://github.com/alugowski/task_thread_pool to the benchmarks.

task_thread_pool is a C++11 thread pool. It's not work-stealing, with performance between BS::thread_pool and the two work-stealing pools.

On my Mac:

| relative |               ms/op |                op/s |    err% |     total | matrix multiplication 256x256
|---------:|--------------------:|--------------------:|--------:|----------:|:------------------------------
|   100.0% |               84.86 |               11.78 |    0.5% |     15.24 | `dp::thread_pool - std::function`
|    69.9% |              121.44 |                8.23 |    4.8% |     21.32 | `BS::thread_pool`
|    71.9% |              118.07 |                8.47 |    5.7% |     21.19 | :wavy_dash: `task_thread_pool` (Unstable with ~16.3 iters. Increase `minEpochIterations` to e.g. 163)
|   117.7% |               72.08 |               13.87 |    3.2% |     12.98 | `riften::Thiefpool`

| relative |               ms/op |                op/s |    err% |     total | matrix multiplication 512x512
|---------:|--------------------:|--------------------:|--------:|----------:|:------------------------------
|   100.0% |               55.32 |               18.08 |    0.4% |      9.92 | `dp::thread_pool - std::function`
|    48.8% |              113.34 |                8.82 |    4.0% |     20.24 | `BS::thread_pool`
|    54.9% |              100.85 |                9.92 |    2.9% |     17.86 | `task_thread_pool`
|   105.6% |               52.37 |               19.09 |    0.4% |      9.44 | `riften::Thiefpool`

[DeveloperPaul123]

@alugowski Thanks for submitting this! Some really interesting results on my machine (Windows 11) with MSVC and Clang 16.
I've updated the benchmark results to reflect the new results with your library. Thanks again!