Bump artifactapi to v3.8.0 (#351)

## Why
artifactapi v3.8.0 ships the github_rpm remote (GitHub releases exposed as a dnf/yum repo via synthesized repodata, a background metadata syncer with multi-replica leasing, and a server-level GitHub machine credential for authenticated requests). This rolls the running deployment onto that release.

## How
- Bump the api image `git.unkin.net/unkin/artifactapi` from v3.7.7 to v3.8.0.
- Bump the ui image `git.unkin.net/unkin/artifactapi-ui` from v3.7.7 to v3.8.0.

---------

Co-authored-by: benvin <neotheo@gmail.com>
Reviewed-on: #351
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

apps/base/artifactapi/api-deployment.yaml

@@ -36,7 +36,7 @@ spec:
               mountPath: /combined-certs
       containers:
         - name: api
-          image: git.unkin.net/unkin/artifactapi:v3.7.7
+          image: git.unkin.net/unkin/artifactapi:v3.8.0
           imagePullPolicy: IfNotPresent
           ports:
             - containerPort: 8000

apps/base/artifactapi/ui-deployment.yaml

@@ -22,7 +22,7 @@ spec:
       automountServiceAccountToken: true
       containers:
         - name: ui
-          image: git.unkin.net/unkin/artifactapi-ui:v3.7.7
+          image: git.unkin.net/unkin/artifactapi-ui:v3.8.0
           imagePullPolicy: IfNotPresent
           ports:
             - containerPort: 80