fix(migrations): set db uri correctly

## Problem
When we swap to docker, we had to swap the `DB_URI` out, which meant that migrations ran using the command weren't working properly.

## Solution
inject env var at command. didn't create separate env file for this cos didn't wanna overload the `.env` files we have alr.

package.json

@@ -16,8 +16,8 @@
     "format-fix": "npx prettier --write .",
     "prepare": "husky install",
     "version": "auto-changelog -p && git add CHANGELOG.md",
-    "db:migrate": "source .env && npx sequelize-cli db:migrate",
-    "db:migrate:undo": "source .env && npx sequelize-cli db:migrate:undo",
+    "db:migrate": "source .env && DB_URI=postgres://isomer:password@localhost:5432/isomercms_dev && npx sequelize-cli db:migrate",
+    "db:migrate:undo": "source .env && DB_URI=postgres://isomer:password@localhost:5432/isomercms_dev && npx sequelize-cli db:migrate:undo",
     "jump:staging": "source .ssh/.env.staging && ssh -L 5433:$DB_HOST:5432 $SSH_USER@$SSH_HOST -i .ssh/isomercms-staging-bastion.pem",
     "db:migrate:staging": "source .ssh/.env.staging && npx sequelize-cli db:migrate",
     "jump:prod": "source .ssh/.env.prod && ssh -L 5433:$DB_HOST:5432 $SSH_USER@$SSH_HOST -i .ssh/isomercms-production-bastion.pem",