Conversion for OpenStackClusterTemplate is missing (v1alpha4 -> v1alpha5, ClusterClass)

[apricote]

/kind bug

What steps did you take and what happened:

• Have existing management cluster running CAPO v0.5
• Create Cluster using ClusterClass
• Upgraded existing management cluster to CAPO v0.6.3
• Check out logs for capo and capi and see following error messages:

From capo-controller-manager:

E0525 08:51:34.722666       1 logr.go:265] conversion-webhook "msg"="failed to convert" "error"="*v1alpha4.OpenStackClusterTemplate is not convertible to *v1alpha5.OpenStackClusterTemplate"  "request"="56491161-28d4-4935-a4c0-4158e95bed44"
E0525 08:51:35.310978       1 logr.go:265] conversion-webhook "msg"="failed to convert" "error"="*v1alpha4.OpenStackClusterTemplate is not convertible to *v1alpha5.OpenStackClusterTemplate"  "request"="216da7ec-b6cd-4a9d-be80-93513abac809"
E0525 08:51:35.404393       1 logr.go:265] conversion-webhook "msg"="failed to convert" "error"="*v1alpha4.OpenStackClusterTemplate is not convertible to *v1alpha5.OpenStackClusterTemplate"  "request"="315f60fa-97bf-4542-a6cb-11af7ab7fd20"

From capi-controller-manager

W0525 08:51:47.248256       1 reflector.go:324] k8s.io/client-go@v0.23.0/tools/cache/reflector.go:167: failed to list infrastructure.cluster.x-k8s.io/v1alpha5, Kind=OpenStackClusterTemplate: conversion webhook for infrastructure.cluster.x-k8s.io/v1alpha4, Kind=OpenStackClusterTemplate failed: *v1alpha4.OpenStackClusterTemplate is not convertible to *v1alpha5.OpenStackClusterTemplate
E0525 08:51:47.248783       1 reflector.go:138] k8s.io/client-go@v0.23.0/tools/cache/reflector.go:167: Failed to watch infrastructure.cluster.x-k8s.io/v1alpha5, Kind=OpenStackClusterTemplate: failed to list infrastructure.cluster.x-k8s.io/v1alpha5, Kind=OpenStackClusterTemplate: conversion webhook for infrastructure.cluster.x-k8s.io/v1alpha4, Kind=OpenStackClusterTemplate failed: *v1alpha4.OpenStackClusterTemplate is not convertible to *v1alpha5.OpenStackClusterTemplate

What did you expect to happen:

Did not expect to see error messages / expected conversion to work for all resources provided by CAPO.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Looks like the flag --conversion was not set when the API types were initially generated. I will work on this ASAP

/assign

Environment:

• Cluster API Provider OpenStack version (Or git rev-parse HEAD if manually built): v0.6.3
• Cluster-API version: v1.1.3
• OpenStack version: /
• Minikube/KIND version: /
• Kubernetes version (use kubectl version): v1.21.12
• OS (e.g. from /etc/os-release): /