Hello !!!!
There are more than 20'Labour Laws' introduced by Govt and are applicable to different kinds of industries and commercial establishments all over India. None of these legislations make any 'Exemption' for I T industries. Therefore, undoubtedly all the 'Labour Laws' are applicable to all types of industries.
As you have mentioned rightly, the I T industry is also 'Manufacturing Industry'. However, there is NO conversion of 'raw material' to 'Finish product'. Therefore, whether 'The Factories Act 1948' could be made applicable to I T industry is a debatable question. Frankly speaking, it must be made applicable to I T industry, as it takes care of 'Safety, Health, Hygiene, Welfare' of employees. All other legislations are undoubtedly applicable to all sorts of Software industries.