chore: Upgrade to Go 1.21 (rebase developer image from ubi/go-toolset to ubi-minimal)

[ckadner]

Motivation

In preparation of the v0.12.0 release of ModelMesh Serving, we need to upgrade from Go 1.20 to Go 1.21 as required by KServe v0.12.0.

Since there will not be a UBI go-toolset image for Go 1.21 until 2Q 2024, we need to "rebase" the Developer image from ubi8/go-toolset:1.20 to ubi8/ubi-minimal:8.9 and install all required tools that would otherwise be provided "out of the box".

Modifications

First step, "rebase" the Developer image from ubi8/go-toolset:1.20 to ubi8/ubi-minimal:8.9 and install Go 1.20.10 along with all required tools. Keep with Go 1.20.10 at first to ensure there are no regressions.

Result

TBD - Work in progress

[ckadner]

@spolti @rafvasq

I am leaving this PR as is:

• rebase dev image (ubi/go-toolset:1:20 => ubi8/ubi-minimal:8.9)
• update Go version (1.20 => 1.21)

I am not yet:

• upgrading KServe (v0.11.2 => v0.12.0-rc1)
• not switching UBI base (ubi8 => ubi9)

In order to keep the changes to a minimum and make it easier to back track should there be unforeseen side effects.

I will create separate PRs for the UBI and KServe upgrades, as the UBI upgrade spans several repositories and the KServe update has a long tail of related changes that require a bit more work.

[oss-prow-bot]

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[oss-prow-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ckadner, rafvasq

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [ckadner,rafvasq]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ckadner]

Thanks @spolti @rafvasq for your reviews