build: Fix typo

meson.build

@@ -66,7 +66,7 @@ conf.set_quoted('PACKAGE_NAME', meson.project_name())
 conf.set_quoted('PACKAGE_STRING', '@0@ - @1@'.format(meson.project_name(), meson.project_version()))
 conf.set_quoted('PACKAGE_VERSION', meson.project_version())
 if get_option('ca_certificates')
-  con.set_quoted('REST_SYSTEM_CA_FILE', ca_certificates_path)
+  conf.set_quoted('REST_SYSTEM_CA_FILE', ca_certificates_path)
 endif
 configure_file(output: 'config.h', configuration: conf)
 config_h_inc = include_directories('.')