replace PhantomData in async_db::Writer

for Send for Writer

lib/src/async_db.rs

@@ -1,4 +1,4 @@
-use std::{marker::PhantomData, path::Path, sync::Arc};
+use std::{path::Path, sync::Arc};
 
 use async_compression::tokio::bufread::ZstdDecoder;
 use async_compression::tokio::write::ZstdEncoder;
@@ -48,7 +48,7 @@ where
     data_buf: Vec<u8>,
     table: Vec<LSize>,
     compress_lvl: Level,
-    _t: PhantomData<*const T>,
+    _t: Option<Arc<T>>, // PhantomData replacement
 }
 
 impl<T> Writer<T>
@@ -69,7 +69,7 @@ where
             data_buf,
             table,
             compress_lvl,
-            _t: PhantomData,
+            _t: None,
         })
     }