Update Dockerfile version (#813)

build/Dockerfile

@@ -1,11 +1,11 @@
-# syntax=docker/dockerfile:1.6
-FROM golang:1.22 as base
+# syntax=docker/dockerfile:1.8
+FROM golang:1.22 AS base
 ARG VERSION
 ARG TARGETARCH
 
 WORKDIR /go/src/github.com/nginxinc/nginx-prometheus-exporter
 
-FROM base as builder
+FROM base AS builder
 COPY --link go.mod go.sum ./
 RUN go mod download
 COPY --link *.go ./
@@ -14,17 +14,17 @@ COPY --link client ./client
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=$TARGETARCH go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION}" -o nginx-prometheus-exporter .
 
 
-FROM scratch as intermediate
+FROM scratch AS intermediate
 COPY --from=base --link /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
 USER 1001:1001
 ENTRYPOINT [ "/usr/bin/nginx-prometheus-exporter" ]
 
 
-FROM intermediate as container
+FROM intermediate AS container
 COPY --from=builder --link /go/src/github.com/nginxinc/nginx-prometheus-exporter/nginx-prometheus-exporter /usr/bin/
 
 
-FROM intermediate as goreleaser
+FROM intermediate AS goreleaser
 ARG TARGETARCH
 ARG TARGETVARIANT
 ARG TARGETPLATFORM