Release 3.0.0

A single new feature: the new log-structured metadata store implementation, described
in the presentation from Moscow Highload'2025 (check it out [here](https://vitastor.io/en/docs/#talks-and-presentations)).

It's now the default store for new OSDs. The support for the old store is also left in place,
you can still choose it for new OSDs with `vitastor-disk prepare --meta_format 2`.

OSDs from previous versions with the old store format will also continue to operate just like before.

src/client/vitastor.pc.in

@@ -6,7 +6,7 @@ includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 
 Name: Vitastor
 Description: Vitastor client library
-Version: 2.4.4
+Version: 3.0.0
 Libs: -L${libdir} -lvitastor_client
 Cflags: -I${includedir}