Bump logback

hotfix 1.2.8 is superseded by 1.2.9 as stated in https://jira.qos.ch/browse/LOGBACK-1591?focusedCommentId=20920&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-20920

pom.xml

@@ -46,7 +46,7 @@
 		<gson.version>2.8.9</gson.version>
 		<zxcvbn.version>1.5.2</zxcvbn.version>
 		<slf4j.version>1.7.32</slf4j.version>
-		<logback.version>1.2.8</logback.version>
+		<logback.version>1.2.9</logback.version>
 
 		<!-- test dependencies -->
 		<junit.jupiter.version>5.8.1</junit.jupiter.version>