all: replace internal rand shim with math/rand/v2

lapack/testlapack/dsyev.go

@@ -5,12 +5,12 @@
 package testlapack
 
 import (
+	"math/rand/v2"
 	"testing"
 
 	"gonum.org/v1/gonum/blas"
 	"gonum.org/v1/gonum/blas/blas64"
 	"gonum.org/v1/gonum/floats"
-	"gonum.org/v1/gonum/internal/rand"
 	"gonum.org/v1/gonum/lapack"
 )
 
@@ -19,7 +19,7 @@ type Dsyever interface {
 }
 
 func DsyevTest(t *testing.T, impl Dsyever) {
-	rnd := rand.New(rand.NewSource(1))
+	rnd := rand.New(rand.NewPCG(1, 1))
 	for _, uplo := range []blas.Uplo{blas.Lower, blas.Upper} {
 		for _, test := range []struct {
 			n, lda int