0.15.1

• add experimental support for libkrun.
• fix check for pidfd availability on older kernels.
• linux: do not set data when remounting read-only. Fix 'ro' mounts on older kernels when SELinux is enabled.
• linux: label the cgroup v1 tmpfs when SELinux is enabled.
• container: truncate the pid file before writing to it.
• exec: fix check for read bytes from the sync socket.
• check the process has a cgroup before allowing pause and resume.
• linux: always create a user namespace if not running with euid == 0.
• libcrun can use a hook instead of executing a container process.
• use libyajl to generate hooks json input.
• handle correctly ENOENT for seccomp notifications.