Pin all rust crates

Cargo's versioning [1] automatically allows patch updates and this has
caused unintentional issues in the past when Cargo/Bazel quietly update
things [2][3].

By applying the =prefix, it means "exactly that version". This pins all
rust crates and updates cxxbridge to match cxx, which is probably a good
idea as those two packages are related. The package bytemuck
was already updated under the hood to 1.23.2, so I pinned it there
(plus v1.16.0 had been yanked/unreleased)

[1] https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html
[2] https://skia-review.googlesource.com/c/skia/+/1043196/comments/dbb481d9_007491a9
[3] https://skia-review.googlesource.com/c/skia/+/1028717

Change-Id: I7931161d0ad15f8bd99a97919e8ad5e45643da75
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1045116
Auto-Submit: Kaylee Lubick <kjlubick@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
Commit-Queue: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
Reviewed-by: Daniel Dilan <danieldilan@google.com>
Commit-Queue: Daniel Dilan <danieldilan@google.com>
2 files changed