kapp deploy mutates created/updated resources twice causing conflicts

**What steps did you take:**

Create a deployment yaml

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 0
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80
```

In another terminal watch deployments
```
kubectl get deployment -w -oyaml
```

**What happened:**
After the deployment is applied kapp immediately updates it - you can see `generation: 2`.

Looking at my k8s service API logs it causes `Conflicts` on creating and updating resources

This is causing to fail deploying at times

```
kapp: Error: Applying update deployment/activator (apps/v1) namespace: 24f0bc17-06dc-424b-a9db-8d4e744d7790:
Failed to update due to resource conflict (approved diff no longer matches):
Updating resource deployment/activator (apps/v1) namespace: 24f0bc17-06dc-424b-a9db-8d4e744d7790:
API server says:
Operation cannot be fulfilled on deployments.apps "activator": the object has been modified; please apply your changes to the latest version and try again (reason: Conflict)
```

**What did you expect:**
`kapp` doesn't mutate resources after they are created/updated

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

**Environment:**

- kapp version (use `kapp --version`): v0.46.0
- OS (e.g. from `/etc/os-release`): Mac OS X/Linux
- Kubernetes version (use `kubectl version`) - K8s 1.21/1.22

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