Update aws-iam-authenticator installation command

[MetalBlueberry]

What this PR does / why we need it:

I was reading the instructions on the readme and the go get command doesn't work outside a module. The go install command is the way to install binaries from anywhere in the system.

Before

go get -u -v sigs.k8s.io/aws-iam-authenticator/cmd/aws-iam-authenticato 
go: go.mod file not found in current directory or any parent directory.
	'go get' is no longer supported outside a module.
	To build and install a command, use 'go install' with a version,
	like 'go install example.com/cmd@latest'
	For more information, see https://golang.org/doc/go-get-install-deprecation
	or run 'go help get' or 'go help install'.

After

go install sigs.k8s.io/aws-iam-authenticator/cmd/[email protected]
go: downloading sigs.k8s.io/aws-iam-authenticator v0.6.27
go: downloading k8s.io/api v0.31.0
go: downloading k8s.io/client-go v0.31.0
go: downloading github.com/spf13/viper v1.7.0
go: downloading k8s.io/apimachinery v0.31.0
go: downloading github.com/aws/aws-sdk-go v1.54.6
go: downloading sigs.k8s.io/yaml v1.4.0
go: downloading k8s.io/sample-controller v0.26.1
go: downloading k8s.io/component-base v0.31.0
go: downloading github.com/manifoldco/promptui v0.9.0
go: downloading github.com/prometheus/client_golang v1.19.1
go: downloading github.com/gofrs/flock v0.8.1
go: downloading golang.org/x/sys v0.21.0
go: downloading github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
go: downloading github.com/magiconair/properties v1.8.1
go: downloading github.com/mitchellh/mapstructure v1.1.2
go: downloading github.com/pelletier/go-toml v1.2.0
go: downloading github.com/spf13/afero v1.1.2
go: downloading github.com/spf13/cast v1.3.0
go: downloading github.com/spf13/jwalterweatherman v1.0.0
go: downloading gopkg.in/ini.v1 v1.51.0
go: downloading k8s.io/klog/v2 v2.130.1
go: downloading github.com/cespare/xxhash/v2 v2.3.0
go: downloading github.com/prometheus/client_model v0.6.1
go: downloading github.com/prometheus/common v0.55.0
go: downloading github.com/prometheus/procfs v0.15.1
go: downloading github.com/google/gofuzz v1.2.0
go: downloading k8s.io/utils v0.0.0-20240711033017-18e509b52bc8
go: downloading golang.org/x/time v0.5.0
go: downloading github.com/imdario/mergo v0.3.16
go: downloading golang.org/x/term v0.21.0
go: downloading golang.org/x/net v0.26.0
go: downloading gopkg.in/inf.v0 v0.9.1
go: downloading sigs.k8s.io/structured-merge-diff/v4 v4.4.1
go: downloading sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd
go: downloading github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822
go: downloading github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da
go: downloading github.com/google/gnostic-models v0.6.8
go: downloading golang.org/x/oauth2 v0.21.0
go: downloading github.com/blang/semver/v4 v4.0.0
go: downloading github.com/fxamacker/cbor/v2 v2.7.0
go: downloading k8s.io/kube-openapi v0.0.0-20240228011516-70dd3763d340
go: downloading github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc
go: downloading github.com/json-iterator/go v1.1.12
go: downloading github.com/modern-go/reflect2 v1.0.2
go: downloading github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd
go: downloading github.com/x448/float16 v0.8.4
go: downloading github.com/go-openapi/jsonreference v0.20.4
go: downloading github.com/emicklei/go-restful/v3 v3.11.0
go: downloading github.com/go-openapi/swag v0.22.7
go: downloading github.com/go-openapi/jsonpointer v0.20.2
go: downloading github.com/mailru/easyjson v0.7.7
go: downloading github.com/josharian/intern v1.0.0

[linux-foundation-easycla[bot]]

• :white_check_mark:login: MetalBlueberry / (cf1740216d70f8325285ab64e18452d0bb49444e)

The committers listed above are authorized under a signed CLA.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @MetalBlueberry. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[bryantbiggs]

/ok-to-test /lgtm

[kmala]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kmala, MetalBlueberry

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