percona-xtrabackup_2_4: 2.4.20 -> 2.4.26

* Unpin stdenv

pkgs/tools/backup/percona-xtrabackup/2_4.nix

···
 { callPackage, ... } @ args:
 
 callPackage ./generic.nix (args // {
-  version = "2.4.20";
-  sha256 = "0awdpkcgvx2aq7pwxy8jyzkin6cyrrh3d576x9ldm851kis9n5ii";
+  version = "2.4.26";
+  sha256 = "sha256-/erBv/Asi/MfoSvAcQ647VAgOfiViPunFWmvy/W9J18=";
 })

pkgs/top-level/all-packages.nix

···
 
   percona-xtrabackup = percona-xtrabackup_8_0;
   percona-xtrabackup_2_4 = callPackage ../tools/backup/percona-xtrabackup/2_4.nix {
-    stdenv = gcc10StdenvCompat;
     boost = boost159;
     openssl = openssl_1_1;
   };