ci: add job checking that upgrade to edition 2024 is trivial

Author: pchickey

.github/workflows/ci.yaml

@@ -192,3 +192,51 @@ jobs:
         run: rustfmt --version
       - name: cargo fmt
         run: cargo fmt --all --check
+
+  edition-2024-upgradable:
+    name: Edition 2024 upgradable
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout source
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+            submodules: true
+      - name: set up cargo cache
+        uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
+        continue-on-error: false
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ runner.os }}-cargo-
+      - name: set up nginx deps cache
+        uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
+        continue-on-error: false
+        with:
+          path: |
+            .cache/.gnupg
+            .cache/nginx
+            .cache/*.tar.gz
+            .cache/*.tar.asc
+            .cache/*.tar.sig
+          key:  ${{ runner.os }}-deps-${{ hashFiles('**/nginx-sys/build.rs') }}
+          restore-keys: ${{ runner.os }}-deps-
+
+      - name: upgrade workspace to edition 2024
+        run: |
+          sed -i 's/edition = "2021"/edition = "2024"/' Cargo.toml
+          sed -i 's/rust-version = "1.82.0"/rust-version = "1.85.0"/' Cargo.toml
+          sed -i 's/Edition2021/Edition2024/' nginx-sys/build/main.rs
+
+      - name: build workspace (all targets, all features)
+        run: cargo build --workspace --all-targets --all-features
+
+      - name: build examples
+        run: cargo build --release --package examples --examples --all-features
+
+      - name: rustdoc
+        run: cargo doc --all-features --no-deps