support upload_time field in wheel metadata

[vlaci]

It got introduced in astral-sh/uv#12968 and released in uv 0.6.15

Without this, lockfile parsing aborts with the following error:

   error: function 'parseWheel' called with unexpected argument 'upload_time'
   at /nix/store/2f6zv2mmb1arvxz1yksakmr6prai4xgm-source/lib/lock1.nix:359:9:
      358|       parseWheel =
      359|         {
         |         ^
      360|           url ? null,