Add nightly linting CI jobs for -Zcheck-cfg and advance notice

.github/workflows/ci.yml

@@ -172,6 +172,29 @@ jobs:
           # Let's not fail CI for this, it will fail locally often enough, and a crate a little bigger
           # than allows is no problem either if it comes to that.
           just check-size || true
+  
+  lint-nightly:
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+          components: clippy,rustfmt
+      - uses: extractions/setup-just@v1
+      - name: Run cargo check -Zcheck-cfg
+        if: '!cancelled()'
+        run: cargo check -Zcheck-cfg
+      - name: Run cargo clippy
+        if: '!cancelled()'
+        run: just clippy -D warnings
+      - name: Run cargo doc
+        if: '!cancelled()'
+        run: just doc
+      - name: Run cargo fmt
+        if: '!cancelled()'
+        run: cargo fmt --all -- --check
 
   cargo-deny:
     runs-on: ubuntu-latest