Fix missing Boost::stl_interfaces dependency in CMakeLists.txt

[sdebionne]

Description

An issue with CMake introduced with the switch to Boost.STLInterfaces:

boost/gil/pixel_iterator_adaptor.hpp includes boost/stl_interfaces/iterator_interface.hpp, but the boost_gil target's link libraries never declared Boost::stl_interfaces. Building gil via a minimal CMake superbuild (BOOST_INCLUDE_LIBRARIES=gil) therefore fails to pull in stl_interfaces at all, causing a missing-header error.

This does not show up with the CI since the tests are build with Boost.Build.

Tasklist

• Ensure all CI builds pass
• Review and approve

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.05%. Comparing base (4d97acb) to head (646df18).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@ Coverage Diff @@## develop #802 +/- ##
===========================================
- Coverage 82.05% 82.05% -0.01% 
===========================================
Files 117 117 Lines 5383 5382 -1 ===========================================
- Hits 4417 4416 -1 
Misses 966 966 

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