Add advisory for race condition in Tokio

[Darksonn]

See tokio-rs/tokio#3929

[Darksonn]

Ah, I just copied the code block from the README.

[Shnatsel]

I can't recall if I implemented the ~ operator. There's a good chance I didn't, and we might have to use a more verbose version specification if I so. I'll add it this Friday now that there is a use case for it.

[Darksonn]

It's past midnight here, so I wont be able to change the tildes until tomorrow.

[Shnatsel]

Properly implementing tildes is tricky, so I don't want to rush that. I've changed the version specification to use version ranges in the meanwhile.

[Shnatsel]

@alex FYI this should have specified >= 1.8.1 instead of ^1.8.1, because the latter would mark 2.0.0 as vulnerable. I've fixed this on main after merging this PR.

[Shnatsel]

Apologies for the inconvenience with the tilde, and thanks for reporting the issue!

To double-check, this is the list of all versions published to crates.io, and whether they're vulnerable or not according to the current version specification, ordered by upload date:

0.0.0 OK
0.1.0 OK
0.1.1 OK
0.1.2 OK
0.1.3 OK
0.1.4 OK
0.1.5 OK
0.1.6 OK
0.1.7 OK
0.1.8 OK
0.1.9 OK
0.1.10 OK
0.1.11 OK
0.1.12 OK
0.1.13 OK
0.1.14 OK
0.1.15 OK
0.1.16 OK
0.1.17 OK
0.1.18 OK
0.1.19 OK
0.1.20 OK
0.1.21 OK
0.1.22 OK
0.2.0-alpha.1 OK
0.2.0-alpha.2 OK
0.2.0-alpha.3 OK
0.2.0-alpha.4 OK
0.2.0-alpha.5 OK
0.2.0-alpha.6 OK
0.2.0 OK
0.2.1 OK
0.2.2 OK
0.2.3 OK
0.2.4 OK
0.2.5 OK
0.2.6 OK
0.2.7 OK
0.2.8 OK
0.2.9 OK
0.2.10 OK
0.2.11 OK
0.2.12 OK
0.2.13 OK
0.2.14 OK
0.2.15 OK
0.2.16 OK
0.2.17 OK
0.2.18 OK
0.2.19 OK
0.2.20 OK
0.2.21 OK
0.2.22 OK
0.3.0 vulnerable
0.3.1 vulnerable
0.3.2 vulnerable
0.3.3 vulnerable
0.2.23 OK
0.3.4 vulnerable
0.3.5 vulnerable
0.2.24 OK
0.3.6 vulnerable
1.0.0 vulnerable
1.0.1 vulnerable
1.0.2 vulnerable
1.1.0 vulnerable
0.2.25 OK
0.3.7 vulnerable
1.0.3 vulnerable
1.1.1 vulnerable
1.2.0 vulnerable
1.3.0 vulnerable
1.4.0 vulnerable
1.5.0 vulnerable
1.6.0 vulnerable
1.6.1 vulnerable
1.6.2 vulnerable
1.7.0 vulnerable
1.7.1 vulnerable
1.8.0 vulnerable
1.5.1 OK
1.6.3 OK
1.7.2 OK
1.8.1 OK