Make build error

[budarin]

go version go1.15.15 linux/amd64
postgres (PostgreSQL) 14.1 (Debian 14.1-1.pgdg110+1)

root@0046bd9d2463:/usr/src/pg_ulid# make
Makefile:25: warning: overriding recipe for target 'pg_ulid.so'
/usr/lib/postgresql/14/lib/pgxs/src/makefiles/../../src/Makefile.shlib:293: warning: ignoring old recipe for target 'pg_ulid.so'
make: Circular pg_ulid.so <- pg_ulid.so dependency dropped.
go build -buildmode=c-shared -o pg_ulid.so main.go pg_ulid.go
pg_ulid.go:10:2: cannot find package "github.com/oklog/ulid" in any of:
/usr/lib/go-1.15/src/github.com/oklog/ulid (from $GOROOT)
/root/go/src/github.com/oklog/ulid (from $GOPATH)
make: *** [Makefile:25: pg_ulid.so] Error 1

[ShonFrazier]

duplicate of #6