CI: install libtool on macos-latest

Author: sstone

.github/workflows/test.yml

@@ -62,7 +62,7 @@ jobs:
           rm.exe "C:/WINDOWS/system32/bash.EXE"
       - name: Install Automake
         if: matrix.os == 'macOS-latest'
-        run: brew install automake
+        run: brew install automake libtool
       - name: Install Automake (windows)
         if: matrix.os == 'windows-latest'
         uses: msys2/setup-msys2@v2