mingw64-libpng from home:mnhauke:mingw:win64:sdr project
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Add repository and install manually
For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:mnhauke:mingw:win64:sdr/openSUSE_Tumbleweed/home:mnhauke:mingw:win64:sdr.repo zypper refresh zypper install mingw64-libpng