ci: Test on more platforms, deny warnings

Author: tgross35

.github/workflows/main.yml

@@ -1,15 +1,23 @@
+env:
+  RUSTFLAGS: "-Dwarnings"
+  RUSTDOCFLAGS: "-Dwarnings"
+
 name: CI
 on: [push, pull_request]
 jobs:
   test:
     name: Test
-    runs-on: ubuntu-latest
     strategy:
       matrix:
-        rust: [stable, beta, nightly]
+        os: [windows-2025, ubuntu-24.04, macos-15]
+        rust: [stable, nightly]
+        include:
+          - os: ubuntu-24.04
+            rust: beta
+    runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@master
-    - name: Install Rust
-      run: rustup update ${{ matrix.rust }} && rustup default ${{ matrix.rust }}
-    - run: cargo test
-    - run: cargo doc
+      - uses: actions/checkout@master
+      - name: Install Rust
+        run: rustup update ${{ matrix.rust }} && rustup default ${{ matrix.rust }}
+      - run: cargo test
+      - run: cargo doc