systemd: Do not check systemd version

The systemd version is purely informational and should not be parsed, as
documented in the [1]. In practice, systemd version has different formats
on OpenShift and Ubuntu.

This commit skips the version check and allows all operations. The errors
will be thrown from dbus when performing unsupported operations on obsolete
versions of systemd.

1: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.systemd1.html

Signed-off-by: Xuewei Niu <niuxuewei.nxw@antgroup.com>

src/lib.rs

@@ -72,22 +72,11 @@ pub mod tests {
         child
     }
 
-    pub fn systemd_version() -> Option<usize> {
+    pub fn systemd_version() -> Option<String> {
         let output = Command::new("systemd").arg("--version").output().ok()?; // Return None if command execution fails
-
         if !output.status.success() {
             return None;
         }
-
-        let stdout = String::from_utf8_lossy(&output.stdout);
-
-        // The first line is typically like "systemd 254 (254.5-1-arch)"
-        let first_line = stdout.lines().next()?;
-        let mut words = first_line.split_whitespace();
-
-        words.next()?; // Skip the "systemd" word
-        let version_str = words.next()?; // The version number as string
-
-        version_str.parse::<usize>().ok()
+        Some(String::from_utf8_lossy(&output.stdout).to_string())
     }
 }