Fix hash_test.go to compile with updated NewParser signature (#268)

NewParser gained an `input string` parameter, but sdks/go/src/hash_test.go
was never updated, so `go test ./src/...` failed to compile. The test only
exercises relationIdFromString, which does not read input, so pass "".

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: hbarthels

sdks/go/src/hash_test.go

@@ -5,7 +5,7 @@ import "testing"
 // TestRelationIdFromString verifies that relation_id_from_string produces
 // the same id across all SDKs (Julia, Python, Go).
 func TestRelationIdFromString(t *testing.T) {
-	p := NewParser([]Token{})
+	p := NewParser([]Token{}, "")
 	rid := p.relationIdFromString("my_relation")
 	if rid.IdLow != 0xf2fc83ec57cf8fbc {
 		t.Errorf("id_low: got 0x%016x, want 0xf2fc83ec57cf8fbc", rid.IdLow)