🌱 Add v1.1 to metadata.yaml

[sbueringer]

What this PR does / why we need it:
This PR adds the upcoming v1.1 release series to the metadata.yaml

I tried to deploy providers via the local repository (generated via cmd/clusterctl/hack/create-local-repository.py which is using the top-level ./metadata.yaml)
and it failed because the release series was missing:

./bin/clusterctl init --core cluster-api:v1.1.99 --bootstrap kubeadm:v1.1.99 --control-plane kubeadm:v1.1.99 --infrastructure docker:v1.1.99 --config ~/.cluster-api/dev-repository/config.yaml
Fetching providers
Error: invalid provider metadata: version v1.1.99 for the provider capi-system/cluster-api does not match any release series

I think we have to add it before the release anyway.

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 #

[sbueringer]

/assign @fabriziopandini

[fabriziopandini]

good catch!
/lgtm
/approve

[k8s-ci-robot]

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