use mlugg/setup-zig instead of goto-bus-stop/setup-zig (#172)

The 'goto-bus-stop' action is no longer maintained and uses outdated
methods for getting the Zig toolchain. Instead use the one maintained by
mlugg, which uses the mirror system and is generally better.

Author: mitchellh

.github/workflows/test.yml

@@ -123,7 +123,7 @@ jobs:
       uses: actions/checkout@v4
 
     - name: Install zig
-      uses: goto-bus-stop/setup-zig@v2
+      uses: mlugg/setup-zig@v2
       with:
         version: 0.14.1
 
@@ -143,7 +143,7 @@ jobs:
       uses: actions/checkout@v4
 
     - name: Install zig
-      uses: goto-bus-stop/setup-zig@v2
+      uses: mlugg/setup-zig@v2
       with:
         version: 0.14.1