Merge pull request #78 from sparkfabrik/000_composer_up

refs #000: Bump default composer version to 2.8.1

Author: grota

Makefile

@@ -1,6 +1,6 @@
 .PHONY: shellcheck
 
-COMPOSER_VERSION ?= 2.5.4
+COMPOSER_VERSION ?= 2.8.1
 
 # build-7-1-11: build-test-image
 # 	docker buildx build --load -t sparkfabrik/docker-php-base-image:7.1.11-fpm-alpine3.4 7.1.11-fpm-alpine3.4