Upgrade to Golang version 1.20.4

[igooch]

What type of PR is this?

/kind cleanup

What this PR does / Why we need it:

Upgrade go version to 1.20.4
Upgrade golangci-lint to the version that introduces support of Golang 1.20
Bump example image tags minor version for examples where Go was upgraded.

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer

Another PR after this will bump the example images version in the places where they are used. After this PR is merged, we need to build the new version of example images and upload the the registry, otherwise the second PR will not pass CI.

[agones-bot]

Build Failed 😱

Build Id: dfb9ebf5-4800-4522-a14b-9a198d4e7854

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• Cloud Build log download

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[agones-bot]

Build Failed 😱

Build Id: 8fa1bde1-ae66-4126-a1b5-d9d0f2c69558

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• Cloud Build log download

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[agones-bot]

Build Succeeded 👏

Build Id: f9240fd5-8a75-429b-9892-c0cd0e6a5e2a

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.32.0-5bdf009-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.32.0-5bdf009-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.32.0-5bdf009-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.32.0-5bdf009-amd64
• Linux C++ SDK (build): agonessdk-1.32.0-5bdf009-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.32.0-5bdf009-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://5bdf009-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3137/head:pr_3137 && git checkout pr_3137
• helm install agones ./install/helm/agones --namespace agones-system --agones.image.release=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.32.0-5bdf009-amd64

[agones-bot]

Build Succeeded 👏

Build Id: 4e7ed519-7aba-497c-a497-0f576419f09e

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.32.0-18815a5-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.32.0-18815a5-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.32.0-18815a5-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.32.0-18815a5-amd64
• Linux C++ SDK (build): agonessdk-1.32.0-18815a5-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.32.0-18815a5-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://18815a5-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3137/head:pr_3137 && git checkout pr_3137
• helm install agones ./install/helm/agones --namespace agones-system --agones.image.release=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.32.0-18815a5-amd64

[gongmax]

LGTM

[google-oss-prow]

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This pull-request has been approved by: gongmax, igooch
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