Skip brew update and upgrade.

.circleci/config.yml

@@ -202,8 +202,6 @@ jobs:
       - run:
           name: Install build dependencies
           command: |
-            brew update
-            brew upgrade
             brew unlink python
             brew install z3
             brew install boost
@@ -353,8 +351,6 @@ jobs:
       - run:
           name: Install dependencies
           command: |
-            brew update
-            brew upgrade
             brew unlink python
             brew install z3
       - run: mkdir -p test_results