Add libtool to MacOS dependencies for github actions (#695)

diff --git a/.github/workflows/action.yml b/.github/workflows/action.yml
index b7ad348..30e0e6b 100644
--- a/.github/workflows/action.yml
+++ b/.github/workflows/action.yml
@@ -69,7 +69,7 @@
         if: startsWith(matrix.os,'macos') && !startsWith(matrix.build-system,'cmake')
         run: |
           brew update
-          brew install automake pkg-config libogg
+          brew install automake pkg-config libogg libtool
 
       - name: Install Linux dependencies
         if: startsWith(matrix.os,'ubuntu')