The following forces any http request to be rewritten using https. For example, the following code forces a request to http://example.com to load https://example.com. It also forces directly linked resources (images, css, etc.) to use https:
Add below into .htaccess file
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301,NE]
Header always set Content-Security-Policy "upgrade-insecure-requests;"
