fix(settings): When testing server stability, request URL with trailing slash

This prevents one HTTP request for most situations (301 from `apps/files` to `apps/files/`)
and helps users with faulty reverse-proxy configuration.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

apps/settings/src/store/apps.js

@@ -197,7 +197,7 @@ const actions = {
 					})
 
 					// check for server health
-					return api.get(generateUrl('apps/files'))
+					return api.get(generateUrl('apps/files/'))
 						.then(() => {
 							if (response.data.update_required) {
 								showInfo(