chore: change heading for confirm email

src/containers/LearnerDashboardHeader/ConfirmEmailBanner/__snapshots__/index.test.jsx.snap

@@ -55,11 +55,11 @@ exports[`ConfirmEmailBanner snapshot Show on unverified 1`] = `
     onClose={[MockFunction closeConfirmModal]}
     title=""
   >
-    <h4
+    <h2
       className="text-center p-3 h1"
     >
       Confirm your email
-    </h4>
+    </h2>
     <p
       className="text-center"
     >

src/containers/LearnerDashboardHeader/ConfirmEmailBanner/index.jsx

@@ -64,7 +64,7 @@ export const ConfirmEmailBanner = () => {
           </Button>
         )}
       >
-        <h4 className="text-center p-3 h1">{formatMessage(messages.confirmEmailModalHeader)}</h4>
+        <h2 className="text-center p-3 h1">{formatMessage(messages.confirmEmailModalHeader)}</h2>
         <p className="text-center">{formatMessage(messages.confirmEmailModalBody)}</p>
       </MarketingModal>
     </>