Update code to work with zig master

.github/workflows/main.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Download zig
       run: |
         export PYTHONIOENCODING=utf8
-        wget https://ziglang.org/builds/zig-linux-x86_64-0.5.0+ae0a219d1.tar.xz
+        wget $(curl -s 'https://ziglang.org/download/index.json' | python3 -c "import sys, json; print(json.load(sys.stdin)['master']['x86_64-linux']['tarball'])")
         sudo apt-get install mtools
         tar -xvf zig*
     - name: Build kernel