Check these 2 things:
The init scripts are triggered only on the first deploy. On the subsequent docker-compose ups you probably see as well on the logs the following message:
db_1  | PostgreSQL Database directory appears to contain a database; Skipping initialization
To force the re-initialization, you can wipe the data volume(This will delete the entries, not only the schema).
To find the path, simply docker inspect <postgres-container-id> and look for the HostConfig.Binds
The script executes till the first type "longvarbinary" does not exist error. You will need to fix this.
db-service_1  | CREATE TABLE
db-service_1  | 2020-07-26 19:29:34.121 UTC [68] ERROR:  type "longvarbinary" does not exist at character 68
I opened a console in the postgres container and your sample database is there, as well as a table that is created before the .sql error occurs in the script:
docker exec -ti 22b0bb87561f sh
# psql -U postgres
psql (11.2 (Debian 11.2-1.pgdg90+1))
Type "help" for help.
postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges   
-----------+----------+----------+------------+------------+-----------------------
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 | 
 sample    | postgres | UTF8     | en_US.utf8 | en_US.utf8 | 
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(4 rows)
postgres=# \c sample
You are now connected to database "sample" as user "postgres".
sample=# \dt
                List of relations
 Schema |         Name         | Type  |  Owner   
--------+----------------------+-------+----------
 public | oauth_client_details | table | postgres
(1 row)