Update debian/watch to format 5

debian/watch

@@ -1,5 +1,4 @@
-
-version=4
-opts="searchmode=plain,filenamemangle=s/$/.tar.gz/" \
-https://api.github.com/repos/latchset/@PACKAGE@/releases \
-    /latchset/@PACKAGE@/releases/download/[^/]+/@PACKAGE@-([0-9][.0-9]*)@ARCHIVE_EXT@
+Version: 5
+Template: Github
+Owner: latchset
+Project: @PACKAGE@