Removed Tailwind build warnings

"purge" was replaced with "content" according to latest TailwindCSS rule & "darkMode" was removed as it is not required coz mentioned while running "yarn run build" or "npm run build" command.

Author: Shubham-Lal

tailwind.config.js

@@ -1,7 +1,6 @@
 module.exports = {
   mode: 'jit',
-  purge: ['./pages/**/*.{js,ts,jsx,tsx}', './components/**/*.{js,ts,jsx,tsx}'],
-  darkMode: false, // or 'media' or 'class'
+  content: ['./pages/**/*.{js,ts,jsx,tsx}', './components/**/*.{js,ts,jsx,tsx}'],
   theme: {
     backgroundColor: theme => ({
       ...theme('colors'),