kubernetes-csi: add Kubernetes 1.20

[pohly]

The prow.sh script has ignored the patch version in the Kubernetes
version number for a while now, therefore we can simplify the
generator script and drop the patch version from all version numbers.

/cc @msau42

[msau42]

we can remove 1.17 as it's not supported anymore.

[pohly]

I was wondering about that too. I kept it because I first wanted to add 1.20 (i.e. always test on three releases), but I agree that combining the removal of the old release with the addition of the new (even if not enabled immediately) cuts down the overall effort - I'll change it.

[msau42]

Has this been removed yet?

[msau42]

hm now we have 4.0 but it requires 1.20 as a min version cc @xing-yang

[pohly]

I suppose we need a switch statement somewhere then?

[xing-yang]

Yeah, maybe set it to 4.0 for 1.20 and higher and set it to 3.0.3 for 1.19 or lower.

[pohly]

So we don't need (or want) to test 3.0.3 on 1.20? Some users might run it there.

That's fine with me, I just wanted to be sure.

[pohly]

Added a Kubernetes check.

[msau42]

/lgtm
/approve

1.17 can be removed as a followup

[k8s-ci-robot]

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This pull-request has been approved by: msau42, pohly

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[k8s-ci-robot]

@pohly: Updated the job-config configmap in namespace default at cluster test-infra-trusted using the following files:

• key csi-driver-host-path-config.yaml using file config/jobs/kubernetes-csi/csi-driver-host-path/csi-driver-host-path-config.yaml
• key external-attacher-config.yaml using file config/jobs/kubernetes-csi/external-attacher/external-attacher-config.yaml
• key external-provisioner-config.yaml using file config/jobs/kubernetes-csi/external-provisioner/external-provisioner-config.yaml
• key external-resizer-config.yaml using file config/jobs/kubernetes-csi/external-resizer/external-resizer-config.yaml
• key external-snapshotter-config.yaml using file config/jobs/kubernetes-csi/external-snapshotter/external-snapshotter-config.yaml
• key livenessprobe-config.yaml using file config/jobs/kubernetes-csi/livenessprobe/livenessprobe-config.yaml
• key node-driver-registrar-config.yaml using file config/jobs/kubernetes-csi/node-driver-registrar/node-driver-registrar-config.yaml

In response to this:

The prow.sh script has ignored the patch version in the Kubernetes
version number for a while now, therefore we can simplify the
generator script and drop the patch version from all version numbers.

/cc @msau42

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