Update CI builds to include emscripten

The CI Windows builds fail... but locally I can't replicate it, so now
I'll try to use ubuntu and build both 🤷

Author: photex

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest]
+        os: [ubuntu-latest]
         backend: [sdl, sokol]
         optimize: [Debug]
     name: Zig Build
@@ -46,6 +46,12 @@ jobs:
           libudev-dev \
           fcitx-libs-dev
 
-    - name: Build All
+    - name: Build Linux
       run: zig build -Dplatform_backend=${{ matrix.backend }} -Doptimize=${{ matrix.optimize }}
 
+    - name: Build Windows
+      run: zig build -Dplatform_backend=${{ matrix.backend }} -Doptimize=${{ matrix.optimize }} -Dtarget=x86_64-windows
+
+    - name: Build Wasm32
+      run: zig build -Dplatform_backend=${{ matrix.backend }} -Doptimize=${{ matrix.optimize }} -Dtarget=wasm32-emscripten
+