Merge bitcoin/bitcoin#31335: macOS: swap docs & CI from pkg-config to pkgconf

fe3457c ci: note that we should install pkgconf in future (fanquake)
8d20348 doc: migrate from pkg-config to pkgconf in macOS build docs (fanquake)

Pull request description:

  Migrate the macOS build docs and CI from `pkg-config` to `pkgconf`. As the former now just redirects to the later.

  Upstream is currently mass-migrating its formula. i.e Homebrew/homebrew-core#198317.

  Fixes #31334.

ACKs for top commit:
  maflcko:
    ACK fe3457c 🍭
  hebasto:
    re-ACK fe3457c.

Tree-SHA512: 6e337acb6767d163491149b6ae7181d7d7042bc11cdc745eb6f52d4df6d7a19c4f6daa000b314acd9178f97e670aba145f829e48b1b3033117d7e39cdd3af177

Author: fanquake

.github/workflows/ci.yml

@@ -109,7 +109,8 @@ jobs:
         run: |
           # A workaround for "The `brew link` step did not complete successfully" error.
           brew install --quiet python@3 || brew link --overwrite python@3
-          brew install --quiet coreutils ninja pkg-config gnu-getopt ccache boost libevent zeromq qt@5 qrencode
+          # Update to install pkgconf, once the GHA image has been updated.
+          brew install --quiet coreutils ninja gnu-getopt ccache boost libevent zeromq qt@5 qrencode
 
       - name: Set Ccache directory
         run: echo "CCACHE_DIR=${RUNNER_TEMP}/ccache_dir" >> "$GITHUB_ENV"

doc/build-osx.md

@@ -48,7 +48,7 @@ See [dependencies.md](dependencies.md) for a complete overview.
 To install, run the following from your terminal:
 
 ``` bash
-brew install cmake boost pkg-config libevent
+brew install cmake boost pkgconf libevent
 ```
 
 ### 4. Clone Bitcoin repository