fix file naming sanitisation

internal/file/zip.go

@@ -3,11 +3,9 @@ package file
 import (
 	"ResendIt/internal/util"
 	"archive/zip"
-	"crypto/rand"
 	"errors"
 	"fmt"
 	"io"
-	"math/big"
 	"mime/multipart"
 	"os"
 	"path/filepath"
@@ -39,17 +37,6 @@ func dedupeName(name string, seen map[string]int) string {
 	return fmt.Sprintf("%s (%d)%s", base, seen[name], ext)
 }
 
-func randIndex(n int) int {
-	if n <= 0 {
-		return 0
-	}
-	x, err := rand.Int(rand.Reader, big.NewInt(int64(n)))
-	if err != nil {
-		return 0
-	}
-	return int(x.Int64())
-}
-
 func cuteZipName(fileCount int) string {
 	adjective := util.RandomAdjective()
 	verb := util.RandomVerb()