update CAPI to v1.2.6 and golang to 1.18.8

[cpanato]

What type of PR is this?

/kind feature

What this PR does / why we need it:

• update CAPI to v1.2.6 and golang to 1.18.8 on release-1.2 branch
  PR from the main branch: update CAPI to v1.2.6 and golang to 1.18.8 #765

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

update CAPI to v1.2.6 and golang to 1.18.8

[cpanato]

/hold for non required tests

/assign @dims @richardcase @sayantani11
after this will do a release for 1.2 series

[dims]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, dims

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[cpanato]

/test ls

[k8s-ci-robot]

@cpanato: The specified target(s) for /test were not found.
The following commands are available to trigger required jobs:

• /test pull-cluster-api-provider-gcp-build-release-1-2
• /test pull-cluster-api-provider-gcp-e2e-test-release-release-1-2
• /test pull-cluster-api-provider-gcp-make-release-release-1-2
• /test pull-cluster-api-provider-gcp-test-release-1-2

The following commands are available to trigger optional jobs:

• /test pull-cluster-api-provider-gcp-capi-e2e-release-release-1-2
• /test pull-cluster-api-provider-gcp-coverage
• /test pull-cluster-api-provider-gcp-make-conformance-release-release-1-2

Use /test all to run the following jobs that were automatically triggered:

• pull-cluster-api-provider-gcp-build-release-1-2
• pull-cluster-api-provider-gcp-e2e-test-release-release-1-2
• pull-cluster-api-provider-gcp-make-release-release-1-2
• pull-cluster-api-provider-gcp-test-release-1-2

In response to this:

/test ls

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[cpanato]

/test pull-cluster-api-provider-gcp-make-conformance-release-release-1-2
/test pull-cluster-api-provider-gcp-capi-e2e-release-release-1-2

[cpanato]

/unhold