Merge branch '5.4'

diff --cc language/de.xml
index 4bcbd71b40cb10d005b23da3c2a912366dbb9989,8dcceba47e1660bb0139a7a6e4713afab6681c3c..090aa10a3e0590decb3f510ee8bdfcd3a7d62e96
--- 1/language/de.xml
--- 2/language/de.xml
+++ b/language/de.xml
@@@ -1,6 -1,5 +1,6 @@@
  <?xml version="1.0" encoding="UTF-8"?>
- <language xmlns="http://www.woltlab.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.woltlab.com http://www.woltlab.com/XSD/2019/language.xsd" languagecode="de">
+ <language xmlns="http://www.woltlab.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.woltlab.com http://www.woltlab.com/XSD/5.4/language.xsd" languagecode="de">
 +<import>
        <category name="wcf.acp.content">
                <item name="wcf.acp.content.provider.com.woltlab.wcf.conversation"><![CDATA[Konversationen]]></item>
                <item name="wcf.acp.content.provider.com.woltlab.wcf.conversation.message"><![CDATA[Konversations-Nachrichten]]></item>

diff --cc language/en.xml
index 080a5d61f8cb2087b6ac09e33f3d4fcb5a851955,d2bc6a217ab7097def1625eb4820eea7ecfc7725..bfcac6b7388644bc839be737bbe47eb35a9b3ba8
--- 1/language/en.xml
--- 2/language/en.xml
+++ b/language/en.xml
@@@ -1,6 -1,5 +1,6 @@@
  <?xml version="1.0" encoding="UTF-8"?>
- <language xmlns="http://www.woltlab.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.woltlab.com http://www.woltlab.com/XSD/2019/language.xsd" languagecode="en">
+ <language xmlns="http://www.woltlab.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.woltlab.com http://www.woltlab.com/XSD/5.4/language.xsd" languagecode="en">
 +<import>
        <category name="wcf.acp.content">
                <item name="wcf.acp.content.provider.com.woltlab.wcf.conversation"><![CDATA[Conversations]]></item>
                <item name="wcf.acp.content.provider.com.woltlab.wcf.conversation.message"><![CDATA[Conversation Messages]]></item>