Make migrations (mostly) idempotent.

config/sql/users.sql

@@ -2,7 +2,7 @@
 
 -- DROP TABLE public.users;
 
-CREATE TABLE public.users
+CREATE TABLE IF NOT EXISTS public.users
 (
   updated timestamp with time zone,
   notifications text[],
@@ -16,13 +16,13 @@ CREATE TABLE public.users
   CONSTRAINT users_email_key UNIQUE (email)
 );
 
-GRANT ALL ON TABLE public.users TO kemal;
+GRANT ALL ON TABLE public.users TO current_user;
 
 -- Index: public.email_unique_idx
 
 -- DROP INDEX public.email_unique_idx;
 
-CREATE UNIQUE INDEX email_unique_idx
+CREATE UNIQUE INDEX IF NOT EXISTS email_unique_idx
   ON public.users
   USING btree
   (lower(email) COLLATE pg_catalog."default");