How many references should be included in the bibliography of a Master thesis?

There is no definite answer. It really depends on how much previous literature exists, how much of it you have reviewed and cited appropriately, and (loosely) what the word count of the document is. Page count can misleading, as some theses have many more figures and tables than others.

No one is going to skip to the bibliography, think negative thoughts, and say "you have too many references!" without reading the document. If no individual part of the thesis could be considered as having too many citations, then the thesis as a whole has an appropriate number of citations.

These related questions have answers as to how you can decide if a particular part of the thesis has too many citations.

• Maximum number of citations per sentence?
• Is there such thing as too many references for one paper?

In addition to the other answer, this question is based on some slightly questionable premises, as seen in the sentence "the total number of citations that is considered normal for a paper (to be more specific, a Master Thesis, which in my case will be around 60 pages of content.)":

• In the communities of CS that I am familiar with, a Master Thesis of some 60 pages is not a paper. A paper is usually a document that concisely describes something on typically 5 to 15 pages (depending both on the paper type (short, full, journal, poster abstract, ...) and the layout. Hence, a Master Thesis is not comparable to a paper.
• Papers published in conferences (and maybe to a somewhat lesser extent, in journals) are usually bound to a very strict upper page count limit. When you have lots of interesting stuff to tell, there is only so much space left for references and you often have to skip citing some sources that you would have liked to include. Such a restriction usually doesn't exist in graduation theses such as Bachelor or Master theses. There may be a rough guideline for the expected number of pages, but exceeding that by a moderate amount (in the case you presented, I'd frankly say 80 pages instead of 60 is ok) if the content is worth it is not necessarily a problem - least of all if the extra length is caused by "additional info" such as the appendix or references rather than the core document.
• Lastly, there is no normal number of references because each topic is different. For some Master Thesis tasks, there may be a number of default works that should always be listed in the initial exposition of the general topic, which in itself already fill a page of references, whereas other Master Thesis tasks might not have such a "default list"; the general exposition is done with very few or without any references.