feat: add a workflow that checks for rust version drift

.github/VERSION_CHECK.md

@@ -0,0 +1,10 @@
+---
+title: "chore: rust toolchain needs an upgrade"
+labels: debt, automated-issues
+---
+
+The rust version specified in `rust-toolchain.toml` is out of date with the latest stable.
+
+Check the [rust version check]({{env.WORKFLOW_URL}}) workflow for details.
+
+This issue was raised by the workflow at `https://github.com/lurk-lab/ci-workflows/tree/main/.github/workflows/rust-version-check.yml`.

.github/workflows/rust-version-check.yml

@@ -0,0 +1,46 @@
+name: Rust Version Check
+
+
+on:
+  workflow_call:
+
+jobs:
+  rust-version-check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Get Local Rust Version
+        id: get-rust-version
+        run: echo "RUST_VERSION=$(rustc --version | awk '{print $2}')" >> $GITHUB_ENV
+
+      - name: Parse rust-toolchain.toml
+        id: parse-toolchain
+        run: |
+          CHANNEL=$(awk -F'\"' '/channel/ {print $2}' rust-toolchain.toml)
+          if [[ $CHANNEL =~ ^[0-9]+\.[0-9]+$ ]]; then
+            echo "TOOLCHAIN_VERSION=$CHANNEL" >> $GITHUB_ENV
+          else
+            echo "TOOLCHAIN_VERSION=stable" >> $GITHUB_ENV
+          fi
+
+      - name: Compare Rust Versions
+        id: compare-versions
+        run: |
+          if [[ $TOOLCHAIN_VERSION != "stable" && $TOOLCHAIN_VERSION < $RUST_VERSION ]]; then
+            echo "VERSION_MISMATCH=true" >> $GITHUB_ENV
+          else
+            echo "VERSION_MISMATCH=false" >> $GITHUB_ENV
+
+      - uses: JasonEtco/create-an-issue@v2
+        if: env.VERSION_MISMATCH == 'true'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          WORKFLOW_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+        with:
+          update_existing: true
+          filename: .github/VERSION_CHECK.md