stack/erp5: adjust aspell usage

We now need to refer to the part where the dictionnary was installed.

stack/erp5/buildout.cfg

@@ -60,7 +60,6 @@ parts +=
   erp5-util-develop
   slapos-cookbook
   rdiff-backup
-  aspell-en-dictionary
   mroonga-mariadb
   tesseract
   tesseract-eng-traineddata
@@ -243,7 +242,7 @@ context =
 [template-zope]
 <= download-base
 link-binary =
-  ${aspell:location}/bin/aspell
+  ${aspell-en-dictionary:bin-aspell}
   ${dmtx-utils:location}/bin/dmtxwrite
   ${git:location}/bin/git
   ${graphviz:location}/bin/dot