doc: Update version to 2.5

Signed-off-by: Jouni Malinen <j@w1.fi>

doc/doxygen.conf

@@ -31,7 +31,7 @@ PROJECT_NAME           = "wpa_supplicant / hostapd"
 # This could be handy for archiving the generated documentation or
 # if some version control system is used.
 
-PROJECT_NUMBER         = 2.4
+PROJECT_NUMBER         = 2.5
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute)
 # base path where the generated documentation will be put.