fix: Check both stderr and stdout for Python version (#66)

* fix python version not showing for version < 3.4

* make review changes

src/modules/python.rs

@@ -46,7 +46,18 @@ pub fn segment(context: &Context) -> Option<Module> {
 
 fn get_python_version() -> Option<String> {
     match Command::new("python").arg("--version").output() {
-        Ok(output) => Some(String::from_utf8(output.stdout).unwrap()),
+        Ok(output) => {
+            // We have to check both stdout and stderr since for Python versions
+            // < 3.4, Python reports to stderr and for Python version >= 3.5,
+            // Python reports to stdout
+            if output.stdout.is_empty() {
+                let stderr_string = String::from_utf8(output.stderr).unwrap();
+                Some(stderr_string)
+            } else {
+                let stdout_string = String::from_utf8(output.stdout).unwrap();
+                Some(stdout_string)
+            }
+        }
         Err(_) => None,
     }
 }