Update to ACK runtime v0.56.0, code-generator v0.56.0 (#61)

### Update to ACK runtime `v0.56.0`, code-generator `v0.56.0`

----------

* ACK code-generator `v0.56.0` [release notes](https://github.com/aws-controllers-k8s/code-generator/releases/tag/v0.56.0)
* ACK runtime `v0.56.0` [release notes](https://github.com/aws-controllers-k8s/runtime/releases/tag/v0.56.0)

----------

NOTE:
This PR increments the release version of service controller from `v1.1.2` to `v1.2.0`

Once this PR is merged, release `v1.2.0` will be automatically created for `ssm-controller`

**Please close this PR, if you do not want the new patch release for `ssm-controller`**

----------

#### stdout for `make build-controller`:

```
building ack-generate ... ok.
==== building ssm-controller ====
Copying common custom resource definitions into ssm
Building Kubernetes API objects for ssm
Generating deepcopy code for ssm
Generating custom resource definitions for ssm
Building service controller for ssm
Running GO mod tidy
Generating RBAC manifests for ssm
Running gofmt against generated code for ssm
Updating additional GitHub repository maintenance files
==== building ssm-controller release artifacts ====
Building release artifacts for ssm-v1.2.0
Generating common custom resource definitions
Generating custom resource definitions for ssm
Generating RBAC manifests for ssm
```

----------

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: ack-bot

.github/workflows/postsubmit.yaml

@@ -0,0 +1,10 @@
+name: Hydrate Go Proxy
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  call-hydrate-go-proxy:
+    uses: aws-controllers-k8s/.github/.github/workflows/reusable-postsubmit.yaml@main