[doc/macos] Improve update-ci script [skip ci]

doc/macos-ci-install/update-ci.sh

 #!/usr/bin/env bash
 
 # Update CI installation
-echo "Updating homebrew..."
+echo "[update-ci] Updating homebrew..."
 brew=/usr/local/bin/brew
 pip=/usr/local/bin/pip3
 if [ ! -x ${brew} ]; then
@@ -9,6 +9,15 @@ if [ ! -x ${brew} ]; then
     pip=/opt/homebrew/bin/pip3
 fi
 ${brew} update
+
+# We now check if gitlab-runner is going to be updated
+gitlab_runner_reconfigure=false
+if [[ $(brew outdated | grep -c "gitlab-runner") != 0 ]]; then
+    echo "[update-ci] The package gitlab-runner is going to be updated (will reconfigure)"
+    gitlab_runner_reconfigure=true
+fi
+
+echo "[update-ci] Upgrading homebrew (outdated) packages..."
 ${brew} upgrade
 
 # A cask upgrade may require sudo, so we cannot do this
@@ -16,6 +25,7 @@ ${brew} upgrade
 #echo "Updating homebrew casks..."
 #${brew} cask upgrade
 
+echo "[update-ci] Cleaning-up homebrew..."
 ${brew} cleanup
 
 # Updates PIP packages installed
@@ -26,3 +36,10 @@ function pipupdate() {
 }
 
 pipupdate ${pip}
+
+# If gitlab-runner was updated, re-configures it
+if [[ "${gitlab_runner_reconfigure}" == "true" ]]; then
+    echo "[update-ci] Reconfiguring gitlab-runner..."
+    /bin/bash <(curl -s https://gitlab.idiap.ch/bob/bob.devtools/raw/master/doc/macos-ci-install/reconfig-gitlab-runner.sh)
+    echo "[update-ci] The gitlab-runner daemon should be fully operational now."
+fi