Fix syntax in pem_cert.pp

This was merged via a private branch because it was a security issue. CI
doesn't run there and this slipped through.

Fixes: 25df787 ("Send passwords via environment variables")

manifests/export/pem_cert.pp

@@ -66,7 +66,7 @@
 
     exec { "Export ${in_cert} to ${pem_cert}":
       command     => $cmd,
-      environment => $passin_env
+      environment => $passin_env,
       path        => $facts['path'],
       *           => $exec_params,
     }