fix: add missing return in GetRequestID

[lin-snow]

Issue

GetRequestID(ctx context.Context) string
function was missing a return statement. This caused a compile error:

missing return at end of function

Solution

Added a return statement so that the function correctly returns
the string value from the context.

func GetRequestID(ctx context.Context) string {
    return ctx.Value(requestIDKey).(string)
}

[lin-snow]

Fixes #78