Add deployment labels to deployment (#649)

### Description of the change

Applies `deployment.labels` to the deployment itself.

### Benefits

Allows the user to add labels to the deployment.

### Possible drawbacks

None

### Checklist

- [X] Parameters are documented in the `values.yaml` and added to the `README.md` using [readme-generator-for-helm](https://github.com/bitnami-labs/readme-generator-for-helm)
- [X] Templating unittests are added

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/649
Reviewed-by: justusbunsi <justusbunsi@noreply.gitea.com>
Co-authored-by: Dalton Russell <dalton.russell@tangramflex.com>
Co-committed-by: Dalton Russell <dalton.russell@tangramflex.com>

templates/gitea/deployment.yaml

@@ -8,6 +8,9 @@ metadata:
     {{- end }}
   labels:
     {{- include "gitea.labels" . | nindent 4 }}
+    {{- if .Values.deployment.labels }}
+    {{- toYaml .Values.deployment.labels | nindent 4 }}
+    {{- end }}
 spec:
   replicas: {{ .Values.replicaCount }}
   strategy:

unittests/deployment/basic.yaml

@@ -15,3 +15,17 @@ tests:
           kind: Deployment
           apiVersion: apps/v1
           name: gitea-unittests
+  - it: deployment labels are set
+    template: templates/gitea/deployment.yaml
+    set:
+      deployment.labels:
+        hello: world
+    asserts:
+      - isSubset:
+          path: metadata.labels
+          content:
+            hello: world
+      - isSubset:
+          path: spec.template.metadata.labels
+          content:
+            hello: world