add gnu grep

Author: philippe-levan

7.2-fpm-alpine/Dockerfile

@@ -19,6 +19,7 @@ RUN apk add --virtual .build-deps $PHPIZE_DEPS --no-cache && \
  nginx \
  wget \
  unzip \
+	grep \
  icu-dev \
  acl \
  libxml2-dev \