Remove Python 3.10 support, update abseil version + change uses of MutexLock

[lanctot]

Delayed until we are ready to remove support for Python 3.10

• Remove Python 3.10 support
• Remove Intel Mac support (causing problems with abseil and PyTorch / JAX stopped supporting it in 2024)
• Update abseil to version 20250814.1
• Update uses of MutexLock(&lock) to MutexLock(lock)

[lanctot]

From https://github.com/google-deepmind/open_spiel/actions/runs/20676631630/job/59365126320 when building the Python 3.10 wheel:

        [ 35%] Built target absl_hashtablez_sampler
        /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: error: aligned allocation function of type 'void *(std::size_t, std::align_val_t)' is only available on macOS 10.13 or newer
          164 |     shared_pools[i] = new RandenPoolEntry();
              |                       ^
        /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: note: if you supply your own aligned allocation functions, use -faligned-allocation to silence this diagnostic
        /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on macOS 10.13 or newer
          164 |     shared_pools[i] = new RandenPoolEntry();
              |                       ^
        /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: note: if you supply your own aligned allocation functions, use -faligned-allocation to silence this diagnostic
        2 errors generated.
        make[3]: *** [abseil-cpp/absl/random/CMakeFiles/absl_random_internal_entropy_pool.dir/internal/entropy_pool.cc.o] Error 1
        make[2]: *** [abseil-cpp/absl/random/CMakeFiles/absl_random_internal_entropy_pool.dir/all] Error 2
        make[2]: *** Waiting for unfinished jobs....
        [ 35%] Linking CXX static library libabsl_flags_program_name.a
        [ 35%] Built target absl_flags_program_name

Unfortunately we have to wait on this until Python 3.10 is removed.

[lanctot]

We might remove Python 3.10 early since it's causing other issues and people can still use older versions. See discussion here: #1419 (comment)

[lanctot]

Same problem:

  [ 31%] Built target absl_crc_cord_state
  [ 31%] Building CXX object abseil-cpp/absl/random/CMakeFiles/absl_random_internal_entropy_pool.dir/internal/entropy_pool.cc.o
  /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: error: aligned allocation function of type 'void *(std::size_t, std::align_val_t)' is only available on macOS 10.13 or newer
    164 |     shared_pools[i] = new RandenPoolEntry();
        |                       ^
  /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: note: if you supply your own aligned allocation functions, use -faligned-allocation to silence this diagnostic
  /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on macOS 10.13 or newer
    164 |     shared_pools[i] = new RandenPoolEntry();
        |                       ^
  /Users/runner/work/open_spiel/open_spiel/open_spiel/abseil-cpp/absl/random/internal/entropy_pool.cc:164:23: note: if you supply your own aligned allocation functions, use -faligned-allocation to silence this diagnostic

This appears to be a problem with abseil and related to MacOS and only on Intel. I will try removing the Intel Mac wheels.