ci: remove zig master ci suport.

only support zig stable release!

Author: jinzhongjia

.github/workflows/zig.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        version: [0.14.0, '']
+        version: [0.14.0, 0.15.1]
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps: