Set version to 4.2.1-dev

Author: brotkrueml

Documentation/guides.xml

@@ -17,7 +17,7 @@
         title="Code Highlight"
         copyright="since 2019 by Chris Müller"
         version="4.2"
-        release="4.2.0"
+        release="4.2.1-dev"
     />
     <inventory
         id="t3coreapi_main"

ext_emconf.php

@@ -8,7 +8,7 @@
     'clearCacheOnLoad' => true,
     'author' => 'Chris Müller',
     'author_email' => 'typo3@brotkrueml.dev',
-    'version' => '4.2.0',
+    'version' => '4.2.1-dev',
     'constraints' => [
         'depends' => [
             'typo3' => '12.4.0-13.4.99',