fix: revert PR #189 due to issues while running inside a Docker container.

Calling the `unshare` syscall is returning `EPERM` error under some circumstances, apparently related to being called inside a Docker container.

For instance, the generation of Python wheels is broken:
https://github.com/VirusTotal/yara-x/actions/runs/10775030489/job/29878522401#step:9:1147

Author: plusvic

Cargo.lock

@@ -246,10 +246,6 @@ yara-x-parser = { workspace = true, features = ["serde"] }
 
 lingua = { version = "1.6.2", optional = true, default-features = false, features = ["english", "german", "french", "spanish"] }
 
-# syscalls crate is only available for Linux
-[target.'cfg(target_os = "linux")'.dependencies]
-syscalls = "0.6.18"
-
 [build-dependencies]
 anyhow = { workspace = true }
 globwalk = { workspace = true }

lib/Cargo.toml

@@ -591,15 +591,6 @@ impl<'r> Scanner<'r> {
         if self.timeout.is_some() {
             INIT_HEARTBEAT.call_once(|| {
                 thread::spawn(|| loop {
-                    #[cfg(target_os = "linux")]
-                    unsafe {
-                        // unshare(CLONE_FS) preventing setns syscall to fail
-                        // if a timeout is set for the scanner.
-                        // see issue: https://github.com/VirusTotal/yara-x/issues/182
-                        syscalls::syscall!(syscalls::Sysno::unshare, 512)
-                            .unwrap();
-                    }
-
                     thread::sleep(Duration::from_secs(1));
                     ENGINE.increment_epoch();
                     HEARTBEAT_COUNTER