Release 2.4.15.0 (1 Sep 2023) -- compared to 2.4.14.0

• bmp: Fix signed integer overflow when computing total number of pixels #3948 (by xiaoxiaoafeifei)
• dds: Fix div by 0 during DXT4 DDS load #3959 (by Jesse Yurkovich)
• rla: Invalid read from an empty vector during RLA load #3960 (by Jesse Yurkovich)
• fix: Various protections against corrupted files #3954
• fix: Improve Utf-8 text rendering #3935 (by Nicolas)
• fix: Fix typo in debug output #3956 (by Jesse Yurkovich)
• ustring.h: String literal operator for ustring and ustringhash #3939
• build Suppress Xcode warnings #3940 (by Anton Dukhovnikov)
• build: Silence gcc new/delete warnings for texturesys #3944 (by Shootfast)
• build Added check for Boost_NO_BOOST_CMAKE, ignore if already set #3961 (by Mikael Sundell)
• build Fix broken libheif < 1.13 #3970
• ci: Make more robust timer_test #3953
• admin: Relicense code under Apache 2.0 #3938 #3966