castai-agent does not support TLS 1.3

[lisenet]

Running a Kubernetes cluster with TLS 1.3 only:

$ curl -vkI https://10.96.0.1:443/api
*   Trying 10.96.0.1:443...
* Connected to 10.96.0.1 (10.96.0.1) port 443 (#0)
* ALPN: offers h2,http/1.1
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
* TLSv1.3 (IN), TLS handshake, Request CERT (13):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.3 (OUT), TLS handshake, Certificate (11):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_128_GCM_SHA256
* ALPN: server accepted h2
* Server certificate:
*  subject: CN=kube-apiserver
*  start date: Jul  5 15:28:54 2023 GMT
*  expire date: Sep 11 09:17:14 2024 GMT
*  issuer: CN=kubernetes
*  SSL certificate verify result: unable to get local issuer certificate (20), continuing anyway.
* using HTTP/2
* h2h3 [:method: HEAD]
* h2h3 [:path: /api]
* h2h3 [:scheme: https]
* h2h3 [:authority: 10.96.0.1]
* h2h3 [user-agent: curl/8.0.1]
* h2h3 [accept: */*]
* Using Stream ID: 1 (easy handle 0x7f1030631af0)
> HEAD /api HTTP/2
> Host: 10.96.0.1
> user-agent: curl/8.0.1
> accept: */*
> 
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
< HTTP/2 405 
HTTP/2 405 
< audit-id: 793432e5-8d19-4714-88f7-b74a1737d9c5
audit-id: 793432e5-8d19-4714-88f7-b74a1737d9c5
< cache-control: no-cache, private
cache-control: no-cache, private
< content-type: application/json
content-type: application/json
< x-kubernetes-pf-flowschema-uid: b7b912df-2347-4ff0-bc46-03db625f6b68
x-kubernetes-pf-flowschema-uid: b7b912df-2347-4ff0-bc46-03db625f6b68
< x-kubernetes-pf-prioritylevel-uid: 91aefef1-aa34-43dd-bcba-e0d14858263e
x-kubernetes-pf-prioritylevel-uid: 91aefef1-aa34-43dd-bcba-e0d14858263e
< content-length: 229
content-length: 229
< date: Thu, 25 Jan 2024 18:18:54 GMT
date: Thu, 25 Jan 2024 18:18:54 GMT

< 
* Connection #0 to host 10.96.0.1 left intact

Castai-agent fails to connect to the API server:

I0125 18:10:12.686315       1 autoscaler.go:46] Scaling namespace: castai-agent, target: deployment/castai-agent
E0125 18:10:12.692345       1 autoscaler.go:49] failed to discover preferred resources: Get https://10.96.0.1:443/api?timeout=32s: remote error: tls: protocol version not supported