Revert ssb-keys replacement and bump ssb-keys version.

The ssb-keys-neon prebuilds work fine, but they don't seem to be
working at all on platforms without prebuilds. This is likely just me not
understanding how to use them properly yet. I'll bring them back once
patchwork is a bit more stable again.

Author: black-puppydog

.github/workflows/main.yml

@@ -19,10 +19,6 @@ jobs:
     steps:
       - run: git config --global core.autocrlf false
       - uses: actions/checkout@v2
-      - name: Set up Rust
-        uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v1
         with: