Added Astrolabe as a tool-used

diff --git a/.pkgmeta b/.pkgmeta
index d0c0583..e9c751a 100644
--- a/.pkgmeta
+++ b/.pkgmeta
@@ -4,5 +4,6 @@ tools-used:
     - ace3
     - callbackhandler
     - libstub
+    - astrolabe

 enable-nolib-creation: no