Rename migration file to match migration revision ID

Because these were slightly different, the `check_if_new_migration`
script would always think there was a new migration to run and so we
were always testing the db migrations when deploying.

migrations/versions/0301_upload_letters_permission.py

@@ -0,0 +1,22 @@
+"""
+
+Revision ID: 0301_upload_letters_permission
+Revises: 0300_migrate_org_types
+Create Date: 2019-08-05 10:49:27.467361
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = '0301_upload_letters_permission'
+down_revision = '0300_migrate_org_types'
+
+
+def upgrade():
+    op.execute("INSERT INTO service_permission_types VALUES ('upload_letters')")
+
+
+def downgrade():
+    op.execute("DELETE FROM service_permissions WHERE permission = 'upload_letters'")
+    op.execute("DELETE FROM service_permission_types WHERE name = 'upload_letters'")