Update to use rand 0.9 throughout

[chuksgpfr]

Chapter 2. Programming a Guessing Game uses thread_rng() and gen_range(), which are deprecated.
I replaced every thread_rng() with rng(), and every gen_range() with random_range()

The function is also referenced in a few other areas, of which I updated.

Since this issue HERE was closed

[chuksgpfr]

@chriskrycho any possibility for this merge, seems quite some people get thrown off when this does not work their way.

[Ahorts]

I was just thinking of opening a PR on this. I wonder why this hasn't been reviewed and merged yet.

[chuksgpfr]

I was just thinking of opening a PR on this. I wonder why this hasn't been reviewed and merged yet.

@chriskrycho People are waiting for this.

[carols10cents]

We're currently working on updating the print version, and updating the rand crate is not going to be part of that. Once we're done with that work, we'll review this.

New versions of rand being released are why we have this note:

Be sure to specify rand exactly as we have here, with this version number, or the code examples in this tutorial
may not work:

If people follow the instructions, there should be no problems.

[552020]

We're currently working on updating the print version, and updating the rand crate is not going to be part of that. Once we're done with that work, we'll review this.

New versions of rand being released are why we have this note:

Be sure to specify rand exactly as we have here, with this version number, or the code examples in this tutorial
may not work:

If people follow the instructions, there should be no problems.

I'm not sure what you mean. Following exactly the instructions of the book (online), "specifyingrand exactly as we have here", doesn't give the same result as in the book because of the deprecation. I mean: you get the same result but you get also the warnings.

[carols10cents]

mean: you get the same result but you get also the warnings.

As you said, you get the same result -- the functionality of the program is not affected. Warnings are just fine, as we state here:

book/src/ch01-01-installation.md

Lines 12 to 14 in b2d1a08

	compile will continue to compile with newer Rust versions. The output might
	differ slightly between versions because Rust often improves error messages and
	warnings. In other words, any newer, stable version of Rust you install using