[13.x] Fix Number::trim() throwing TypeError when passed INF or NAN

[romdh4ne]

Number::trim() uses json_decode(json_encode($number)) internally.
However, json_encode(INF) and json_encode(NAN) return false in PHP
since these are not valid JSON values. json_decode(false) then returns
null, which violates the declared return type int|float and throws
a Fatal TypeError.

How to reproduce

Number::trim(INF);  // Fatal TypeError: Return value must be of type int|float, null returned
Number::trim(NAN);  // Fatal TypeError: Return value must be of type int|float, null returned

Fix

Guard with is_finite() before encoding. Non-finite values are returned
as-is since there are no trailing zeros to trim.