nixosTests.miniflux: fix test

This broke in 41c5662cbec9930b337a895c7cb010948d9766a9, where $PSQL was
removed and added to PATH instead.

Changed files
+1 -1
nixos
tests
+1 -1
nixos/tests/miniflux.nix
···
'';
};
systemd.services.postgresql-setup.postStart = lib.mkAfter ''
-
$PSQL -tAd miniflux -c 'CREATE EXTENSION hstore;'
+
psql -tAd miniflux -c 'CREATE EXTENSION hstore;'
'';
networking.firewall.allowedTCPPorts = [ config.services.postgresql.settings.port ];
};