Fix Docker warnings

cmd/fluent-manager/Dockerfile

@@ -1,7 +1,7 @@
 ARG GO_VERSION=1.24.5
 
 # Build the manager binary \
-FROM --platform=$BUILDPLATFORM golang:${GO_VERSION}-alpine3.21 as builder
+FROM --platform=$BUILDPLATFORM golang:${GO_VERSION}-alpine3.21 AS builder
 
 WORKDIR /workspace
 # Copy the Go Modules manifests

cmd/fluent-watcher/fluentbit/Dockerfile

@@ -1,7 +1,7 @@
 ARG FLUENT_BIT_BASE_VERSION=3.2.4 \
     GO_VERSION=1.24.5
 
-FROM golang:${GO_VERSION}-alpine3.21 as buildergo
+FROM golang:${GO_VERSION}-alpine3.21 AS buildergo
 RUN mkdir -p /fluent-bit
 RUN mkdir -p /code
 COPY . /code/

cmd/fluent-watcher/fluentbit/Dockerfile.debug

@@ -1,7 +1,7 @@
 ARG FLUENT_BIT_BASE_VERSION=3.2.4 \
     GO_VERSION=1.24.5
 
-FROM golang:${GO_VERSION}-alpine3.21 as buildergo
+FROM golang:${GO_VERSION}-alpine3.21 AS buildergo
 RUN mkdir -p /fluent-bit
 RUN mkdir -p /code
 COPY . /code/

cmd/fluent-watcher/fluentd/Dockerfile

@@ -1,7 +1,7 @@
 ARG FLUENTD_BASE_VERSION \
     GO_VERSION=1.24.5
 
-FROM golang:${GO_VERSION} as builder
+FROM golang:${GO_VERSION} AS builder
 
 RUN mkdir -p /fluentd
 RUN mkdir -p /code

docs/best-practice/forwarding-logs-via-http/Dockerfile

@@ -1,6 +1,6 @@
 GO_VERSION=1.24.5
 # Build the manager binary
-FROM golang:${GO_VERSION} as builder
+FROM golang:${GO_VERSION} AS builder
 
 WORKDIR /
 COPY main.go /go/src/main.go