Having that is not a priority since it can be done via phpmyadmin.
Your serialized data is not valid.
When you see that:
s:19:"shipping_min_weight";s:4:"0.01";
the first part which is "s" indicates that you're looking at a string. The second part, 19, indicates the length of the string and then you have the string in the third parameter. So you have 19 because shipping_min_weight has 19 letters.
And as you can see, the value of that parameter has four characters: 0.01
So if you change the values there, you also need to change the letters count.
Thus, s:0:"20" is not possible. It should be s:2:"20".
If you use :
O:8:"stdClass":14:{s:19:"shipping_percentage";s:1:"0";s:18:"shipping_min_price";s:0:"";s:18:"shipping_max_price";s:0:"";s:25:"shipping_virtual_included";s:1:"0";s:19:"shipping_min_weight";s:4:"0.01";s:19:"shipping_max_weight";s:2:"20";s:20:"shipping_weight_unit";s:1:"g";s:19:"shipping_zip_prefix";s:0:"";s:16:"shipping_min_zip";s:0:"";s:16:"shipping_max_zip";s:0:"";s:19:"shipping_zip_suffix";s:0:"";s:19:"shipping_min_volume";s:0:"";s:19:"shipping_max_volume";s:0:"";s:18:"shipping_size_unit";s:1:"m";}
in the unserializer tool I gave you, it will display the data unserialized while with what you have now, it just says that the data is not valid.