time-util,socket: accept both kinds of unicode µ symbols

time-util,socket: accept both kinds of unicode µ symbols

Apparently there are two µ symbols, accept both when parsing.

One is the greek small letter mu (μ) the other is the micro sign (µ).
Unicode recommendation considers both equivalent, and says use of greek
small letter mu is preferred. See:

https://www.unicode.org/reports/tr25

Hence accept both when parsing.

Inspired by: #28029