refactor: remove unnecessary dark mode text color classes from header and footer

Author: wKovacs64

src/footer.tsx

@@ -4,7 +4,7 @@ function Footer() {
   return (
     <footer className="flex justify-center">
       <a
-        className="group p-2 dark:text-gray-100"
+        className="group p-2"
         href="https://github.com/wKovacs64/pwl"
         rel="noopener noreferrer"
       >

src/header.tsx

@@ -20,7 +20,7 @@ function Header() {
           Password Lense
         </h1>
         <button
-          className="group absolute top-4 right-4 p-2 dark:text-gray-100"
+          className="group absolute top-4 right-4 p-2"
           type="button"
           onClick={handleThemeToggle}
         >