Specify the public schema for public videos

Unlike the other migrations, this one uses a bare table name to specify the table. This means it looks in the default search path. Unfortunately, the out of box search path is:

1. Schema with the same name as the user
2. Public

Because of this, if a schema exists with the same name as the DB user, the playlist_videos table will get created in _that_ schema, rather than the public schema, and then the grant statement will fail with an error like below if check_table is enabled as it keeps trying to create the table but failing on the grant statement:

```
2022-01-22 02:27:42 UTC [info] check_table: check_table: CREATE TABLE playlist_videos
Unhandled exception: relation "public.playlist_videos" does not exist (PQ::PQError)
  from /usr/share/crystal/src/primitives.cr:266:3 in 'handle_error'
  from lib/pg/src/pq/connection.cr:184:9 in 'handle_async_frames'
  from lib/pg/src/pq/connection.cr:162:7 in 'read'
  from lib/pg/src/pq/query.cr:53:14 in 'exec_all'
  from lib/db/src/db/database.cr:126:9 in '__crystal_main'
  from /usr/share/crystal/src/crystal/main.cr:110:5 in 'main'
  from src/env/__libc_start_main.c:94:2 in 'libc_start_main_stage2'
2022-01-22 02:27:43 UTC [info] check_table: check_table: CREATE TABLE playlist_videos
Unhandled exception: relation "public.playlist_videos" does not exist (PQ::PQError)
  from /usr/share/crystal/src/primitives.cr:266:3 in 'handle_error'
  from lib/pg/src/pq/connection.cr:184:9 in 'handle_async_frames'
  from lib/pg/src/pq/connection.cr:162:7 in 'read'
  from lib/pg/src/pq/query.cr:53:14 in 'exec_all'
  from lib/db/src/db/database.cr:126:9 in '__crystal_main'
  from /usr/share/crystal/src/crystal/main.cr:110:5 in 'main'
  from src/env/__libc_start_main.c:94:2 in 'libc_start_main_stage2'
```

config/sql/playlist_videos.sql

@@ -2,7 +2,7 @@
 
 -- DROP TABLE public.playlist_videos;
 
-CREATE TABLE IF NOT EXISTS playlist_videos
+CREATE TABLE IF NOT EXISTS public.playlist_videos
 (
     title text,
     id text,