WhenAnonymousUserOpenNotExistingCategoryPage: fix URL of testing page.

Should be in 221b8e5 commit.

No functional changes.

Author: php-coder

src/test/java/ru/mystamps/web/tests/cases/WhenAnonymousUserOpenNotExistingCategoryPage.java

@@ -42,7 +42,7 @@ public void shouldShow404Page() {
 		String absentCategoryId = "888";
 		String url = Url.INFO_CATEGORY_PAGE
 			.replace("{id}", absentCategoryId)
-			.replace("slug", "category-404-error-test");
+			.replace("{slug}", "category-404-error-test");
 		page.open(url);
 
 		checkStandardStructure();