update WordPress dependency

Author: pfefferle

phpcs.xml

@@ -14,7 +14,7 @@
 	<config name="testVersion" value="7.0-"/>
 	<rule ref="WordPress-Core" />
 	<rule ref="PHPCompatibilityWP"/>
-	<config name="minimum_supported_wp_version" value="4.9"/>
+	<config name="minimum_supported_wp_version" value="6.3"/>
 	<rule ref="WordPress.WP.DeprecatedFunctions" />
 	<rule ref="WordPress.Files.FileName">
 		<properties>

readme.md

@@ -3,7 +3,7 @@
 - Contributors: pfefferle, dshanske, indieweb
 - Donate link: https://notiz.blog/donate/
 - Tags: webmention, pingback, trackback, linkback, indieweb
-- Requires at least: 4.9
+- Requires at least: 6.3
 - Tested up to: 6.7
 - Stable tag: 5.3.3
 - Requires PHP: 7.0