Fix macOS CI.

Download zlib from the github release.
Hopefully this URL will be stable.
Remove those failing brew invocations.
Remove unneeded dependencies in the Brewfile.

.github/workflows/main.yml

@@ -616,23 +616,16 @@ jobs:
       - name: Install dependencies
         env:
           # For compatibility with macOS 10.13
-          ZLIB_VERSION: 1.3
+          ZLIB_VERSION: 1.3.1
           MBEDTLS_VERSION: 2.28.5
           PCRE2_VERSION: 10.42
         run: |
           set -ex
-          brew uninstall openssl@1.0.2t || echo
-          brew uninstall python@2.7.17 || echo
-          brew untap local/openssl || echo
-          brew untap local/python2 || echo
           brew update
-          # brew unlink python@2
-          brew bundle --file=tests/Brewfile --no-upgrade || brew link --overwrite awscli
-          brew install libunistring
-          brew install cpanminus
+          brew bundle --file=tests/Brewfile --no-upgrade
           cpanm IPC::System::Simple
           cpanm String::ShellQuote
-          curl -L https://www.zlib.net/zlib-$ZLIB_VERSION.tar.gz | tar xz
+          curl -L https://github.com/madler/zlib/releases/download/v$ZLIB_VERSION/zlib-$ZLIB_VERSION.tar.gz | tar xz
           cd zlib-$ZLIB_VERSION
           ./configure
           make && make install

extra/github-actions/build-mac.yml

@@ -1,23 +1,16 @@
 - name: Install dependencies
   env:
     # For compatibility with macOS 10.13
-    ZLIB_VERSION: 1.3
+    ZLIB_VERSION: 1.3.1
     MBEDTLS_VERSION: 2.28.5
     PCRE2_VERSION: 10.42
   run: |
     set -ex
-    brew uninstall openssl@1.0.2t || echo
-    brew uninstall python@2.7.17 || echo
-    brew untap local/openssl || echo
-    brew untap local/python2 || echo
     brew update
-    # brew unlink python@2
-    brew bundle --file=tests/Brewfile --no-upgrade || brew link --overwrite awscli
-    brew install libunistring
-    brew install cpanminus
+    brew bundle --file=tests/Brewfile --no-upgrade
     cpanm IPC::System::Simple
     cpanm String::ShellQuote
-    curl -L https://www.zlib.net/zlib-$ZLIB_VERSION.tar.gz | tar xz
+    curl -L https://github.com/madler/zlib/releases/download/v$ZLIB_VERSION/zlib-$ZLIB_VERSION.tar.gz | tar xz
     cd zlib-$ZLIB_VERSION
     ./configure
     make && make install

tests/Brewfile

@@ -1,7 +1,6 @@
-brew "ocaml"
-brew "camlp5"
 brew "opam"
 brew "ninja"
-brew "awscli"
 brew "cmake"
-brew "pkg-config"
+brew "pkg-config"
+brew "libunistring"
+brew "cpanminus"