software/erp5: fix tmpdir in caucase partition

This was introduced recently, in 0aecb41a (software: Use local tmp for
caucase, 2021-05-18). This is harmless, but uses a weird-looking directory

stack/erp5/buildout.hash.cfg

@@ -74,7 +74,7 @@ md5sum = bbef65b4edeb342f08309604ca3717d5
 
 [template-erp5]
 filename = instance-erp5.cfg.in
-md5sum = 49b7e029c7fca7c95d3bfd8876d1a632
+md5sum = fcc8470824c448a56e2282c43b870cb5
 
 [template-zeo]
 filename = instance-zeo.cfg.in

stack/erp5/instance-erp5.cfg.in

@@ -71,7 +71,7 @@ recipe = slapos.cookbook:mkdirectory
 bin = ${buildout:directory}/bin
 service-on-watch = ${buildout:directory}/etc/service
 srv = ${buildout:directory}/srv
-tmp = {$buildout:directory}/tmp
+tmp = ${buildout:directory}/tmp
 backup-caucased = ${:srv}/backup/caucased
 
 {% if not caucase_url -%}