Update displayRules.ts

Add `thefilter` to the list of sections for which we are not showing a sign-in gate.

And example of Filter article is: https://www.theguardian.com/thefilter/2025/aug/17/tempur-pro-plus-smartcool-mattress-review

Author: shtukas

dotcom-rendering/src/components/SignInGate/displayRules.ts

@@ -33,6 +33,7 @@ export const isValidSection = (sectionId?: string): boolean => {
 		'help',
 		'guardian-live-australia',
 		'gnm-archive',
+		'thefilter',
 	];
 
 	// we check for invalid section by reducing the above array, and then NOT the result so we know