Remove seeds from heroku app json file

Co-authored-by: Vinicius Negrisolo <vinicius.negrisolo@hashrocket.com>
Co-authored-by: Gabriel Reis <gabriel.reis@hashrocket.com>

Author: 3 people

app.json

@@ -1,7 +1,7 @@
 {
   "name": "tilex",
   "scripts": {
-    "postdeploy": "mix ecto.migrate && POOL_SIZE=1 mix run priv/repo/seeds.exs"
+    "postdeploy": "POOL_SIZE=1 mix ecto.migrate"
   },
   "env": {
     "BASIC_AUTH_PASSWORD": {