fix: deprecated Dockerfile ENV syntax #1003

Job	Run time
prepare	9s
build (php-8-2-20-alpine, linux/amd64)	9m 47s
build (php-8-2-20-alpine, linux/386)	9m 54s
build (php-8-2-20-alpine, linux/arm/v6)	20m 26s
build (php-8-2-20-alpine, linux/arm/v7)	20m 32s
build (php-8-2-20-alpine, linux/arm64)	27m 54s
build (php-8-2-20-bookworm, linux/amd64)	2m 29s
build (php-8-2-20-bookworm, linux/386)	2m 25s
build (php-8-2-20-bookworm, linux/arm/v7)	14m 40s
build (php-8-2-20-bookworm, linux/arm64)	13m 40s
build (php-8-3-8-alpine, linux/amd64)	9m 6s
build (php-8-3-8-alpine, linux/386)	8m 32s
build (php-8-3-8-alpine, linux/arm/v6)	19m 57s
build (php-8-3-8-alpine, linux/arm/v7)	21m 41s
build (php-8-3-8-alpine, linux/arm64)	27m 50s
build (php-8-3-8-bookworm, linux/amd64)	5m 11s
build (php-8-3-8-bookworm, linux/386)	3m 20s
build (php-8-3-8-bookworm, linux/arm/v7)	14m 24s
build (php-8-3-8-bookworm, linux/arm64)	13m 59s
push	0s
	4h 5m 56s

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