build: Bump ssh2 from 0.9.3 to 0.9.4

Bumps [ssh2](https://github.com/alexcrichton/ssh2-rs) from 0.9.3 to 0.9.4.
- [Release notes](https://github.com/alexcrichton/ssh2-rs/releases)
- [Commits](https://github.com/alexcrichton/ssh2-rs/compare/0.9.3...0.9.4)

---
updated-dependencies:
- dependency-name: ssh2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Cargo.lock

@@ -569,9 +569,9 @@ checksum = "201de327520df007757c1f0adce6e827fe8562fbc28bfd9c15571c66ca1f5f79"
 
 [[package]]
 name = "libssh2-sys"
-version = "0.2.23"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b094a36eb4b8b8c8a7b4b8ae43b2944502be3e59cd87687595cf6b0a71b3f4ca"
+checksum = "2dc8a030b787e2119a731f1951d6a773e2280c660f8ec4b0f5e1505a386e71ee"
 dependencies = [
  "cc",
  "libc",
@@ -1195,9 +1195,9 @@ checksum = "a507befe795404456341dfab10cef66ead4c041f62b8b11bbb92bffe5d0953e0"
 
 [[package]]
 name = "ssh2"
-version = "0.9.3"
+version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "269343e64430067a14937ae0e3c4ec604c178fb896dde0964b1acd22b3e2eeb1"
+checksum = "e7fe461910559f6d5604c3731d00d2aafc4a83d1665922e280f42f9a168d5455"
 dependencies = [
  "bitflags",
  "libc",