fix(curriculum): remove stray backtick from greeting card instructions (freeCodeCamp#61634)

Co-authored-by: Trev Abbott <trevabbott@MacBookPro.lan>

Author: vibemeistert

curriculum/challenges/english/25-front-end-development/workshop-greeting-card/6720b7f3155a9278d6b6a8b8.md

@@ -35,7 +35,7 @@ You should set `padding` to `40px` in the `body` selector.
 assert.strictEqual(new __helpers.CSSHelp(document).getStyle("body")?.getPropertyValue("padding"), "40px");
 ```
 
-You should set `text-align` to `center` in the `body` selector.`
+You should set `text-align` to `center` in the `body` selector.
 
 ```js
 assert.strictEqual(new __helpers.CSSHelp(document).getStyle("body")?.getPropertyValue("text-align"), "center");