* Remove legacy HPKE version

We no longer have logs generated with version `2` so we can just drop
the legacy HPKE version support.

* Bump dependencies

The version bump for `hpke` doesn't result in breaking changes.

* Bump crate dependencies

Update to clap `3.0.0-beta.4` required implementing `ArgEnum`
for the arg enums previosuly using `Clap`.

* Fix new clippy errors

* Overhaul decrypt subcommand arguments

This patch changes the arguments for the decrypt subcommand:
- The encrypted matched data argument is now a positional argument.
- Both the encrypted matched data and private key arguments now expect a
filename. Passing `-` as the positional argument leads to the data
data being read from stdin.
- The argument `--private-key-stdin` has been removed.

* Add documentation and blog post links to README

* Bump Rust edition to 2021

* Bump dependencies

Only `clap` has a breaking change and required modifications.

* Remove generic-array

* Move assert deps to dev-dependencies

* Update clap to 3.0.0

* Update hpke to v0.8.0

…are#19)

Matched data may get truncated for some events, meaning the string would be set to `truncated` instead of the usual blob. This adds support for that case.

Also bumps dependencies to mitigate the issues reported by `cargo audit`.

Co-authored-by: Shreya Shetty <shreya@cloudflare.com>

Bumps [regex](https://github.com/rust-lang/regex) from 1.5.4 to 1.5.6.
- [Release notes](https://github.com/rust-lang/regex/releases)
- [Changelog](https://github.com/rust-lang/regex/blob/master/CHANGELOG.md)
- [Commits](rust-lang/regex@1.5.4...1.5.6)

---
updated-dependencies:
- dependency-name: regex
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Create semgrep.yml

Creating Semgrep.yml file - Semgrep is a tool that will be used to scan Cloudflare's public repos for Supply chain, code and secrets. This work is part of Application & Product Security team's initiative to onboard Semgrep onto all of Cloudflare's public repos.

In case of any questions, please reach out to "Hrushikesh Deshpande" on cf internal chat.

* Update semgrep.yml