Fix primary-key constraint name on add-ps-team-member

[Re #1611]

* Otherwise it wouldn't match the name real constraint name on the
database and thus not throw the expected error.

backend/src/gpml/db/plastic_strategy/team.clj

@@ -30,7 +30,7 @@
   [conn ps-team-member]
   (jdbc-util/with-constraint-violation-check
     [{:type :unique
-      :name "plastic_strategy_team_member_pkey"
+      :name "plastic_strategy_team_pkey"
       :error-reason :already-exists}]
     (add-ps-team-member* conn (ps-team-member->p-ps-team-member ps-team-member))
     {:success? true}))