revert release url being nullable, we dont need it

src/util/entities/ClientRelease.ts

@@ -30,8 +30,8 @@ export class Release extends BaseClass {
 	@Column()
 	pub_date: Date;
 
-	@Column({ nullable: true })
-	url: string | null;
+	@Column()
+	url: string;
 
 	@Column()
 	platform: string;

src/util/schemas/responses/UpdatesResponse.ts

@@ -32,9 +32,8 @@ export interface UpdatesResponse {
 	pub_date: string;
 	/**
 	 * The URL to the corresponding installer.
-	 * Only provided if auto updates are available for the selected platform.
 	 */
-	url: string | null;
+	url: string;
 	/**
 	 * Any extra notes for the update
 	 * Only provided if auto updates are available for the selected platform.