build-sys: fix meson project version usage

Program wixl found: YES (/usr/bin/wixl)

../qga/meson.build:149:16: ERROR: Unknown variable "project".

Fixes: e20d68aa0b ("configure, meson: use command line options to configure qemu-ga")
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>

qga/meson.build

@@ -146,7 +146,7 @@ if targetos == 'windows'
       libpcre = 'libpcre2'
     endif
     qga_msi_version = get_option('qemu_ga_version') == '' \
-      ? project.version() \
+      ? meson.project_version() \
       : get_option('qemu_ga_version')
     qga_msi = custom_target('QGA MSI',
                             input: files('installer/qemu-ga.wxs'),