fix: allow concurrent access to dc_sqlite3_t

src/dc_move.rs

@@ -16,7 +16,7 @@ pub unsafe fn dc_do_heuristics_moves(
     let mut stmt: *mut sqlite3_stmt = 0 as *mut sqlite3_stmt;
     if !(dc_sqlite3_get_config_int(
         context,
-        &mut context.sql.clone().lock().unwrap(),
+        &context.sql.clone().read().unwrap(),
         b"mvbox_move\x00" as *const u8 as *const libc::c_char,
         1i32,
     ) == 0i32)