github: Install cmake

We need it to build libsql with encryption enabled.

Author: penberg

.github/workflows/CI.yml

@@ -65,6 +65,10 @@ jobs:
         target: [aarch64]
     steps:
       - uses: actions/checkout@v3
+      - name: Setup cmake
+        uses: jwlawson/actions-setup-cmake@v1.14
+        with:
+          cmake-version: '3.18.x'
       - uses: actions/setup-python@v4
         with:
           python-version: '3.10'