don't crash on brew update (#2138)

* don't crash on brew update

* don't update (again) on brew install ccache

* rm 2to3 before. force true on install, too

* rm 2to3 and others; don't update

* dont rm anything ; just install ccache with no update

.github/workflows/continuous.yml

@@ -55,8 +55,7 @@ jobs:
       - name: Dependencies (macOS)
         if: runner.os == 'macOS'
         run: |
-          brew update
-          brew install ccache
+          HOMEBREW_NO_AUTO_UPDATE=1 brew install ccache
 
       - name: Cache Build
         id: cache-build