shepherd: update update-archive script

update_archive-pubmed.sh

@@ -1,2 +1,2 @@
 #!/bin/sh
-/bin/su -l hchen -c 'export EDIRECT_PUBMED_MASTER=/export2/PubMed; export PERL_LWP_SSL_CA_FILE=/etc/ssl/certs/ca-certificates.crt; export NLTK_DATA=/export2/PubMed/nltk_data; export PATH=$(/var/guix/profiles/per-user/shepherd/current-guix/bin/guix build edirect-gn)/bin:$PATH; $(/var/guix/profiles/per-user/shepherd/current-guix/bin/guix build edirect-gn)/bin/archive-pubmed'
+/bin/su -l hchen -c 'export EDIRECT_PUBMED_MASTER=/export2/PubMed; export PERL_LWP_SSL_CA_FILE=/etc/ssl/certs/ca-certificates.crt; export NLTK_DATA=/export2/PubMed/nltk_data; unset PATH; $(/var/guix/profiles/per-user/shepherd/current-guix/bin/guix build edirect-gn)/bin/archive-pubmed'