style: fix warning during docker build

[davidxia]

by addressing the warning below.

make container
...

 2 warnings found (use --debug to expand):
 - FromAsCasing: 'as' and 'FROM' keywords' casing do not match (line 3)

How does this change affect the cardinality of KSM: does not change cardinality

[dgrisonnet]

/assign
/triage accepted

@davidxia which tool are you using to verify the Dockerfile?

[davidxia]

This was output I saw with make container. I'm using

docker version
Client: Docker Engine - Community
 Version:           26.1.3
 API version:       1.45
 Go version:        go1.21.10
 Git commit:        b72abbb
 Built:             Thu May 16 08:33:49 2024
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Engine - Community
 Engine:
  Version:          26.1.3
  API version:      1.45 (minimum version 1.24)
  Go version:       go1.21.10
  Git commit:       8e96db1
  Built:            Thu May 16 08:33:49 2024
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.33
  GitCommit:        d2d58213f83a351ca8f528a95fbd145f5654e957
 runc:
  Version:          1.1.12
  GitCommit:        v1.1.12-0-g51d5e94
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

[mrueg]

/lgtm

[k8s-ci-robot]

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