Bump our macOS CI runners

.github/scripts/install_deps.sh

@@ -2,7 +2,7 @@
 # This script requires `sh` instead of `bash` because the latter is not always installed on FreeBSD.
 set -eu
 
-case "${1%-*}" in
+case "${1%%-*}" in
 	ubuntu|debian)
 		sudo apt-get -qq update
 		sudo apt-get install -yq bison libpng-dev pkgconf
@@ -14,7 +14,8 @@ case "${1%-*}" in
 		brew install bison md5sha1sum make
 		# Export `bison` to allow using the version we install from Homebrew,
 		# instead of the outdated one preinstalled on macOS (which doesn't even support `-Wall`...)
-		export PATH="/opt/homebrew/opt/bison/bin:$PATH"
+		# This path  ↓ is used on Intel macOS, and this one ↓ on ARM ones.
+		export PATH="/usr/local/opt/bison/bin:/opt/homebrew/opt/bison/bin:$PATH"
 		printf 'PATH=%s\n' "$PATH" >>"$GITHUB_ENV" # Make it available to later CI steps too
 		;;
 	freebsd)
@@ -27,7 +28,8 @@ case "${1%-*}" in
 		bison() { win_bison "$@"; } # An alias doesn't work, so we use a function instead.
 		;;
 	*)
-		echo "::error:: Cannot install deps for OS '$1'"
+		echo "Cannot install deps for OS '$1'"
+		exit 1
 		;;
 esac