feat(keychain): support >2.9 (#13189)

Co-authored-by: Carlo Sala <carlosalag@protonmail.com>

plugins/keychain/keychain.plugin.zsh

@@ -19,8 +19,15 @@ function {
 	# load additional options
 	zstyle -a :omz:plugins:keychain options options
 
-	# start keychain...
+	# Check keychain version to decide whether to use --agents
+	local version_string=$(keychain --version 2>&1 | head -n 2 | tail -n 1 | cut -d ' ' -f 4)
+  # start keychain, only use --agents for versions below 2.9.0
+	autoload -Uz is-at-least
+	if is-at-least 2.9 "$version_string"; then
 		keychain ${^options:-} --agents ${agents:-gpg} ${^identities} --host $SHORT_HOST
+	else
+		keychain ${^options:-} ${^identities} --host $SHORT_HOST
+	fi
 
 	# Get the filenames to store/lookup the environment from
 	_keychain_env_sh="$HOME/.keychain/$SHORT_HOST-sh"