CI: install GNU tar on Alpine runner (deploy test uses tar --transform, BusyBox tar does not support it; apk tar gives GNU tar 1.35)

.gitea/workflows/ci.yaml

@@ -5,7 +5,7 @@ jobs:
     runs-on: host
     steps:
       - name: install python
-        run: apk add --no-cache python3 py3-pip ca-certificates git curl github-cli 2>&1 | tail -3; python3 --version; git --version
+        run: apk add --no-cache python3 py3-pip ca-certificates git curl github-cli tar 2>&1 | tail -3; python3 --version; git --version
       - name: clone repo
         run: |
           rm -rf src