Release v3.0.0-rc7

See https://github.com/haampie/libtree/blob/release/3.0/CHANGELOG.md

087226c69472a1cab61f38b78a157a6441e1ae859bae20c2d91977695e38b042  libtree_aarch64
40f2db85623178b91ae8eae8e91fc815191accd73abdd749cd0e55e2971a4864  libtree_armv6l
5be45efd474b8e117d62f3ae01ab5a0f7f40888000607a0b54b8e794d61da620  libtree_armv7l
1031fbda8c0b3bc943fe32120eeeedb0d736247c285b8f0f69e61d85c264d5b9  libtree_i686
995abae57821f7529d72ee1650ae81422917ce933d7ecf0c35bc9d5f9d2dd761  libtree_powerpc64le
f8d36ef12a2895ee8f54a7c94f1f12f23406353b7f9e229f97e094e54be640b2  libtree_x86_64
b4910a9a8a9e952670f66f5ab24e2a2bd8c22f2012089054082b596f675bfc79  libtree_x86_64-freebsd