Switched from RustCrypto to OpenSSL.

* OpenSSL supports a lot more ciphers and algorithms. It also has a lot
  more hardware-level optimizations like AVX and Neon.
* OpenSSL can be updated (patched) without rebuilding the app.
* OpenSSL has a more active maintenance cycle and is likely the first
  one to receive security patches.
* OpenSSL (or its forks) are used by most Rust TLS implementations.
* RustCrypto's TLS client is in its infancy, with certificate validation
  being especially unpolished.

.github/workflows/cargo-build.yml

@@ -26,6 +26,7 @@ jobs:
           ~/.cargo/registry/index
           ~/.cargo/registry/cache
           ~/.cargo/git/db
+          ~/.cargo/bin
           ${{ github.workspace }}/target
         key: lint-${{ runner.os }}-${{ steps.get-rust-version.outputs.VERSION }}-${{ hashFiles('Cargo.*') }}
 
@@ -74,7 +75,7 @@ jobs:
       run: |
         rustup target add ${{ matrix.arch }}-unknown-linux-gnu
         sudo apt-get update
-        sudo apt-get install -y crossbuild-essential-arm64 qemu-user-static
+        sudo apt-get install -y crossbuild-essential-arm64 qemu-user-static openssl-dev:arm64
         echo "LD_LIBRARY_PATH=/usr/aarch64-linux-gnu/lib:$LD_LIBRARY_PATH" >> $GITHUB_ENV
         echo "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=/usr/bin/aarch64-linux-gnu-gcc" >> $GITHUB_ENV
         echo "CC=/usr/bin/aarch64-linux-gnu-gcc" >> $GITHUB_ENV