Added Micro Sign Support in parseTimeDelta Function

Added support for the micro sign (U+00B5) in the parseTimeDelta function. Now both the micro sign (U+00B5) and the Greek letter mu (U+03BC) are recognized as valid representations for microseconds, aligning ClickHouse's behavior with Go’s implementation (see time.go and time/format.go). #75472 (Vitaly Orlov).