Signed/unsigned comparison

[meshula]

Bug Report

Incorrect Functionality

/opt/OpenTimelineIO/source/src/opentimelineio/imageSequenceReference.cpp: In member function ‘std::string opentimelineio::v1_0::ImageSequenceReference::target_url_for_image_number(int, opentimelineio::v1_0::ErrorStatus*) const’:
/opt/OpenTimelineIO/source/src/opentimelineio/imageSequenceReference.cpp:90:39: warning: comparison of integer expressions of different signedness: ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} and ‘const int’ [-Wsign-compare]
   90 |         if (image_num_string.length() <  _frame_zero_padding) {
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

[ssteinbach]

Fixed by #889