Fix for gcc-13 build failure (#180)

The error was:
  lib/radio_model.h:176:99: error: ‘uint32_t’ has not been declared

Fix is to "#include <cstdint>"

client/mumble-plugin/lib/radio_model.h

@@ -14,6 +14,7 @@
  * You should have received a copy of the GNU General Public License 
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
+#include <cstdint>
 #include <iostream> 
 #include <cmath>
 #include <regex>