Create a CI script for automated releases

.github/workflows/release.yml

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+name: Release
+
+on:
+  push:
+    branches:
+      - 'master'
+
+jobs:
+  release:
+    name: "Release"
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    environment: crates_io_release
+
+    steps:
+      - name: "Checkout Repository"
+        uses: actions/checkout@v1
+
+      - name: "Install Python Libraries"
+        run: python -m pip install --user -r requirements.txt
+        working-directory: "scripts"
+
+      - name: "Run release script"
+        run: "python3 scripts/ci-release.py"
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

scripts/ci-release.py

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+import toml
+import requests
+import subprocess
+
+cargo_toml = toml.load("Cargo.toml")
+crate_version = cargo_toml["package"]["version"]
+print("Detected crate version " + crate_version)
+
+api_url = "https://crates.io/api/v1/crates/x86_64/versions"
+crates_io_versions = requests.get(api_url).json()
+
+new_version = True
+for version in crates_io_versions["versions"]:
+    assert (version["crate"] == "x86_64")
+    if version["num"] == crate_version:
+        new_version = False
+        break
+
+if new_version:
+    print("Could not find version " + crate_version + " on crates.io; creating a new release")
+
+    print("  Running `cargo publish`")
+    subprocess.run(["cargo", "publish"], check=True)
+
+    tag_name = "v" + crate_version
+    print("  Tagging commit as " + tag_name)
+    sha = subprocess.run(["git", "rev-parse", "HEAD"], check=True, stdout=subprocess.PIPE).stdout.decode("utf-8").strip()
+    subprocess.run([
+        "gh", "api", "/repos/rust-osdev/x86_64/git/refs",
+        "-X", "POST", "-H", "Accept: application/vnd.github.v3+json",
+        "-F", "ref=refs/tags/" + tag_name,
+        "-F", "sha="+sha
+    ])
+
+    print("  Done")
+else:
+    print("Version " + crate_version + " already exists on crates.io")

scripts/requirements.txt

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+toml