CI: Configure cmake generator to be set to ninja.

git-svn-id: https://svn.rinrab.com/rinrab/xdigest/trunk@6346 0083e6b4-6090-234a-836e-88fcc467669c

Author: rinrab

.github/workflows/cmake.yml

@@ -14,7 +14,7 @@ jobs:
 
     - run: sudo apt-get install gcc-multilib lib32stdc++6
 
-    - run: cmake -B out-x64 -DCMAKE_INSTALL_PREFIX=install/x64
+    - run: cmake -B out-x64 -G Ninja -DCMAKE_INSTALL_PREFIX=install/x64
     - run: ninja -C out-x64
     - run: ninja -C out-x64 install
     - run: ninja -C out-x64 test