Remove SMW requirement from composer.json (#787)

Of course SMW is required for SRF to run, but the presence of this line makes it impossible for SMW and SRF to both be downloaded via a non-Composer option like Git, because then calling "composer install" for SRF, in order to get its dependencies, will lead to SMW getting re-downloaded. The line doesn't seem necessary, anyway.

composer.json

@@ -46,7 +46,6 @@
 	"require": {
 		"php": ">=7.3",
 		"composer/installers": ">=1.0.1",
-		"mediawiki/semantic-media-wiki": "~3.0|~4.0|~5.0",
 		"nicmart/tree": "^0.2.7",
 		"data-values/geo": "~4.0|~3.0|~2.0"
 	},