Address code smells in Dockerfile (#31)

db/migrations.go

@@ -26,10 +26,10 @@ func RunMigrationsDown(pg *pgxpool.Pool) error {
 // the database updated with the latest changes in either direction,
 // up or down.
 func runMigrations(pg *pgxpool.Pool, direction migrate.MigrationDirection) error {
-	_db := stdlib.OpenDB(*pg.Config().ConnConfig)
+	db := stdlib.OpenDB(*pg.Config().ConnConfig)
 
 	var migrations = &migrate.PackrMigrationSource{Box: packrMigrations}
-	nMigrations, err := migrate.Exec(_db, "postgres", migrations, direction)
+	nMigrations, err := migrate.Exec(db, "postgres", migrations, direction)
 	if err != nil {
 		return err
 	}

docker/Dockerfile

@@ -12,7 +12,11 @@ RUN go mod download
 
 # Build binary
 COPY . .
-RUN cd ./db && packr2 && cd ../
+
+WORKDIR /go/src/github.com/0xPolygon/beethoven/db
+RUN packr2
+
+WORKDIR /go/src/github.com/0xPolygon/beethoven
 RUN make build
 
 # CONTAINER FOR RUNNING BINARY