psi/psi_test.go: not wrapp tstStr in []byte

stream/mts/psi/psi_test.go

@@ -367,7 +367,7 @@ func TestTrim(t *testing.T) {
 // for pmts with time and location, as the location data field is 32 bytes, i.e. quite large
 // to type out
 func buildPmtWithMeta(tstStr string) []byte {
-	pmt := append(pmtWithMetaHead, []byte(tstStr)...)
+	pmt := append(pmtWithMetaHead, tstStr...)
 	pmt = append(pmt, pmtWithMetaTail...)
 	return pmt
 }