glfw: CI: clone submodules

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

.github/workflows/ci.yml

@@ -13,6 +13,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+        with:
+          submodules: 'true'
       - name: Setup Zig
         run: |
           sudo apt install xz-utils
@@ -39,6 +41,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+        with:
+          submodules: 'true'
       - name: Setup Zig
         run: |
           $ProgressPreference = 'SilentlyContinue'
@@ -62,6 +66,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+        with:
+          submodules: 'true'
       - name: Setup Zig
         run: |
           brew uninstall --ignore-dependencies libx11 # https://github.com/ziglang/zig/issues/11066