Add missing untestable test.

tests/untestable/tpostgres.nim

@@ -0,0 +1,13 @@
+import db_postgres
+
+let db = open("localhost", "dom", "", "test")
+db.exec(sql"DROP TABLE IF EXISTS myTable")
+db.exec(sql("""CREATE TABLE myTable (
+                  id integer PRIMARY KEY,
+                  name varchar(50) not null)"""))
+let name = "Dom"
+db.exec(sql"INSERT INTO myTable (id, name) VALUES (0, ?)",
+        name)
+doAssert db.getValue(sql"SELECT name FROM myTable") == name
+
+db.close()