fix: add systemtime_as_secs

src/systemtime_as_secs.rs

@@ -0,0 +1,9 @@
+use std::time::SystemTime;
+
+pub fn as_secs(t: &SystemTime) -> u64 {
+    match t.duration_since(SystemTime::UNIX_EPOCH) {
+        Ok(duration) => duration,
+        Err(err) => err.duration(),
+    }
+    .as_secs()
+}