Run modernize (#21546)

`go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...` executed.

`go generate ./...` ran afterwards to keep generated.

internal/auth/credentials_test.go

@@ -25,7 +25,7 @@ import (
 
 func TestExpToInt64(t *testing.T) {
 	testCases := []struct {
-		exp             interface{}
+		exp             any
 		expectedFailure bool
 	}{
 		{"", true},
@@ -42,7 +42,6 @@ func TestExpToInt64(t *testing.T) {
 	}
 
 	for _, testCase := range testCases {
-		testCase := testCase
 		t.Run("", func(t *testing.T) {
 			_, err := ExpToInt64(testCase.exp)
 			if err != nil && !testCase.expectedFailure {