benchmark submodule not based on v1.7.1 or newer

[louis-langholtz]

Expected/Desired Behavior or Experience:

Benchmark application builds with cmake without errors nor warnings and uses google benchmark tagged v1.7.1 - i.e. is more up to date for 2/9/2023.

Actual Behavior:

Some points:

• Benchmark in master branch is building with a version of google benchmark tagged v1.3.0 from 11/3/2017.
• Seeing build issues of Benchmark application via cmake:

Build issues - at least on one platform - are:

[ 81%] Building CXX object Benchmark/benchmark/src/CMakeFiles/benchmark.dir/benchmark.cc.o
[ 82%] Building CXX object Benchmark/benchmark/src/CMakeFiles/benchmark.dir/benchmark_register.cc.o
[ 83%] Building CXX object Benchmark/benchmark/src/CMakeFiles/benchmark.dir/colorprint.cc.o
[ 84%] Building CXX object Benchmark/benchmark/src/CMakeFiles/benchmark.dir/commandlineflags.cc.o
[ 85%] Building CXX object Benchmark/benchmark/src/CMakeFiles/benchmark.dir/complexity.cc.o
/Volumes/LDL-User-Data/check/PlayRho/Benchmark/benchmark/src/complexity.cc:79:10: error: variable 'sigma_gn' set but not used [-Werror,-Wunused-but-set-variable]
  double sigma_gn = 0.0;
         ^
1 error generated.
make[2]: *** [Benchmark/benchmark/src/CMakeFiles/benchmark.dir/complexity.cc.o] Error 1
make[1]: *** [Benchmark/benchmark/src/CMakeFiles/benchmark.dir/all] Error 2
make: *** [all] Error 2

Steps to Reproduce the Actual Behavior:

git clone --recurse-submodules https://github.com/louis-langholtz/PlayRho.git
mkdir PlayRho-build
cd PlayRho-build
cmake -DPLAYRHO_BUILD_BENCHMARK=ON ../PlayRho
make