[CLI-3333] Make email address for SSO case insensitive (#2965)

pkg/auth/auth_token_handler.go

@@ -4,6 +4,7 @@ package auth
 import (
 	"context"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/pkg/browser"
@@ -230,7 +231,7 @@ func (a *AuthTokenHandlerImpl) checkSSOEmailMatchesLogin(client *ccloudv1.Client
 	if err != nil {
 		return err
 	}
-	if getMeReply.GetUser().GetEmail() != loginEmail {
+	if strings.EqualFold(getMeReply.GetUser().GetEmail(), loginEmail) {
 		return errors.NewErrorWithSuggestions(
 			fmt.Sprintf("expected SSO credentials for %s but got credentials for %s", loginEmail, getMeReply.GetUser().GetEmail()),
 			"Please re-login and use the same email at the prompt and in the SSO portal.",