参考：
https://golang.org/doc/go1.121.12 的 release 包中关于 fmt 的修改：
fmt
Maps are now printed in key-sorted order to ease testing. The ordering rules are:
When applicable, nil compares low
ints, floats, and strings order by <
NaN compares less than non-NaN floats
bool compares false before true
Complex compares real, then imaginary
Pointers compare by machine address
Channel values compare by machine address
Structs compare each field in turn
Arrays compare each element in turn
Interface values compare first by reflect.Type describing the concrete type and then by concrete value as described in the previous rules.
When printing maps, non-reflexive key values like NaN were previously displayed as <nil>. As of this release, the correct values are printed.