Convert XHTML meta tags to HTML5 format

Co-authored-by: honzajavorek <283441+honzajavorek@users.noreply.github.com>

Author: Copilot

docs/_templates/page.html

@@ -12,7 +12,7 @@
 
 {%- block extrahead %}
   {{ super() }}
-  <meta property="og:image" content="{{ pathto('_static/images/org.svg', 1) }}" />
-  <meta property="og:image:type" content="image/svg+xml" />
-  <meta property="og:image:alt" content="Ilustrace organizátora Python akcí" />
+  <meta property="og:image" content="{{ pathto('_static/images/org.svg', 1) }}">
+  <meta property="og:image:type" content="image/svg+xml">
+  <meta property="og:image:alt" content="Ilustrace organizátora Python akcí">
 {%- endblock -%}