Merge bitcoin/bitcoin#29610: ci: Fix "macOS native" job

acc06bc91f ci, macos: Use `--break-system-packages` with Homebrew's python (Hennadii Stepanov)
ae5f72027f ci: Add workaround for Homebrew's python link error (Hennadii Stepanov)

Pull request description:

  Homebrew [promoted](https://github.com/Homebrew/homebrew-core/pull/150390) `python@3.12` to the default `python3`. Now, our "macOS native" CI job is facing the following issues:

  1. Installing `qt@5` [requires](https://github.com/bitcoin/bitcoin/actions/runs/8216848118/job/22471875454#step:4:51) re-installing `python@3.12`:
  ```
  ==> Fetching dependencies for qt@5: readline, python@3.12 and gettext
  ```
  2. Re-installing `python@3.12` [fails](https://github.com/bitcoin/bitcoin/actions/runs/8216848118/job/22471875454#step:4:127) due to symbolic link conflicts on macOS `x86_64`:
  ```
  ==> Pouring python@3.12--3.12.2_1.ventura.bottle.tar.gz
  Error: The `brew link` step did not complete successfully
  ```
  3. Homebrew's `python@3.12` is marked as externally managed (according to PEP 668), necessitating different approaches for installing Python packages.

  This pull request resolves all the issues mentioned above.

ACKs for top commit:
  m3dwards:
    reACK acc06bc91f to get the CI passing again.

Tree-SHA512: 82cf72bff328f1e0725342431ac14ad4bae7a758186d97db6c7a558e4b661dcbf3fabe536978e26e709c5f6f7f5c11aac46642634c6685f1291592d8d825ad87

.github/workflows/ci.yml

@@ -96,7 +96,10 @@ jobs:
       - name: Install Homebrew packages
         env:
           HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK: 1
-        run: brew install automake libtool pkg-config gnu-getopt ccache boost libevent miniupnpc libnatpmp zeromq qt@5 qrencode
+        run: |
+          # A workaround for "The `brew link` step did not complete successfully" error.
+          brew install python@3 || brew link --overwrite python@3
+          brew install automake libtool pkg-config gnu-getopt ccache boost libevent miniupnpc libnatpmp zeromq qt@5 qrencode
 
       - name: Set Ccache directory
         run: echo "CCACHE_DIR=${RUNNER_TEMP}/ccache_dir" >> "$GITHUB_ENV"

ci/test/00_setup_env_mac_native.sh

@@ -7,7 +7,9 @@
 export LC_ALL=C.UTF-8
 
 export HOST=x86_64-apple-darwin
-export PIP_PACKAGES="zmq"
+# Homebrew's python@3.12 is marked as externally managed (PEP 668).
+# Therefore, `--break-system-packages` is needed.
+export PIP_PACKAGES="--break-system-packages zmq"
 export GOAL="install"
 export BITCOIN_CONFIG="--with-gui --with-miniupnpc --with-natpmp --enable-reduce-exports"
 export CI_OS_NAME="macos"