Update XWiki mid-year LTS version (#15129)

library/xwiki

@@ -31,3 +31,19 @@ Tags: 14-mariadb-tomcat, 14.10-mariadb-tomcat, 14.10.14-mariadb-tomcat, lts-mari
 Architectures: amd64, arm64v8
 Directory: 14/mariadb-tomcat
 GitCommit: 0bd38a7fd96d995c5d8ea6ad53b302b3b21058d7
+
+# Mid-year "LTS" (done by XWiki SAS developers and not official). To be removed when the next official LTS is released.
+Tags: 15.5, 15.5.1, 15.5-mysql-tomcat, 15.5.1-mysql-tomcat
+Architectures: amd64, arm64v8
+Directory: 15.5/mysql-tomcat
+GitCommit: 280bb2f94c270db7b9cab529ef639fc46e90e868
+
+Tags: 15.5-postgres-tomcat, 15.5.1-postgres-tomcat
+Architectures: amd64, arm64v8
+Directory: 15.5/postgres-tomcat
+GitCommit: 280bb2f94c270db7b9cab529ef639fc46e90e868
+
+Tags: 15.5-mariadb-tomcat, 15.5.1-mariadb-tomcat
+Architectures: amd64, arm64v8
+Directory:  15.5/mariadb-tomcat
+GitCommit: 280bb2f94c270db7b9cab529ef639fc46e90e868