Fixes -Wrange-loop-construct warning in GCC 11 (#188)
Fixes -Wrange-loop-construct warning in GCC 11 (#188)

This should be covered by the reference lifetime extension,
but it is a new warning nonetheless.

time_zone_format_test.cc:1138:27: error: loop variable 'prec' of type
'const string&' {aka 'const std::__cxx11::basic_string<char>&'} binds
to a temporary constructed from type 'const char* const'
[-Werror=range-loop-construct]
google/cctz,google/cctz