CI: only run on Zig master branch

Author: Techatrix

.github/workflows/main.yml

@@ -14,7 +14,6 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        zig-version: [latest, master]
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
@@ -24,7 +23,7 @@ jobs:
       - name: Setup Zig
         uses: mlugg/setup-zig@v2
         with:
-          version: ${{ matrix.zig-version }}
+          version: master
 
       - name: Check Formatting
         run: zig fmt --ast-check --check .