Feed doesn't generate valid RFC-3339 dates

<?xml version="1.0" encoding="UTF-8"?>

<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en-gb">

    <link rel="self" type="application/atom+xml" href="http://www.try-phpbb.com/33x/app.php/feed/news" />    <title>yourdomain.com</title>

    <subtitle>Default username/password: administrator/administrator</subtitle>

    <link href="http://www.try-phpbb.com/33x/index.php" />

    <updated>2019-12-31T14:34:17</updated>    <author><name><![CDATA[yourdomain.com]]></name></author>

    <id>http://www.try-phpbb.com/33x/app.php/feed/news</id>        <entry>

        <author><name><![CDATA[administrator]]></name></author>

        <updated>2019-12-31T14:34:17</updated>        <published>2019-12-31T14:34:17</published>

        <id>http://www.try-phpbb.com/33x/viewtopic.php?p=1#p1</id>

        <link href="http://www.try-phpbb.com/33x/viewtopic.php?p=1#p1"/>

        <title type="html"><![CDATA[Welcome to phpBB3]]></title>                    <category term="Your first forum" scheme="http://www.try-phpbb.com/33x/viewforum.php?f=2" label="Your first forum"/>

        <content type="html" xml:base="http://www.try-phpbb.com/33x/viewtopic.php?p=1#p1"><![CDATA[

This is an example post in your phpBB3 installation. Everything seems to be working. You may delete this post if you like and continue to set up your board. During the installation process your first category and your first forum are assigned an appropriate set of permissions for the predefined usergroups administrators, bots, global moderators, guests, registered users and registered COPPA users. If you also choose to delete your first category and your first forum, do not forget to assign permissions for all these usergroups for all new categories and forums you create. It is recommended to rename your first category and your first forum and copy permissions from these while creating new categories and forums. Have fun!<p>Statistics: Posted by <a href="http://www.try-phpbb.com/33x/memberlist.php?mode=viewprofile&amp;u=2">administrator</a> — Tue Dec 31, 2019 2:34 pm — Replies 0 — Views 2</p><hr />

]]></content>

    </entry>

    </feed> 

Sorry

This feed does not validate.

line 8, column 29: updated must be an RFC-3339 date-time: 2019-12-31T14:34:17 [help]	<updated>2019-12-31T14:34:17</updated>

                             ^

line 15, column 30: updated must be an RFC-3339 date-time: 2019-12-31T14:34:17 [help]		<updated>2019-12-31T14:34:17</updated>

                              ^

line 17, column 32: published must be an RFC-3339 date-time: 2019-12-31T14:34:17 [help]		<published>2019-12-31T14:34:17</published>

                                ^

In addition, interoperability with the widest range of feed readers 

could be improved by implementing the following recommendation.

line 3, column 102: Self reference doesn't match document location [help]... .try-phpbb.com/33x/app.php/feed/news" />

                                             ^