forgejo-ci: drop 3.19 builder, add 3.21

.forgejo/workflows/build-v3.21.yaml

@@ -3,7 +3,7 @@ on:
     types: [ assigned, opened, synchronize, reopened ]
 
 jobs:
-  build-v3.19:
+  build-v3.21:
     runs-on: x86_64
     container:
       image: alpinelinux/alpine-gitlab-ci:latest
@@ -12,7 +12,7 @@ jobs:
       CI_DEBUG_BUILD: ${{ runner.debug }}
       CI_MERGE_REQUEST_PROJECT_URL: ${{ github.server_url }}/${{ github.repository }}
       CI_MERGE_REQUEST_TARGET_BRANCH_NAME: ${{ github.base_ref }}
-      CI_ALPINE_TARGET: v3.19
+      CI_ALPINE_TARGET: v3.21
     steps:
       - name: Environment setup
         run: |
@@ -33,14 +33,14 @@ jobs:
           name: package
           path: packages
 
-  deploy-v3.19:
-    needs: [build-v3.19]
+  deploy-v3.21:
+    needs: [build-v3.21]
     runs-on: x86_64
     container:
       image: alpine:latest
     env:
+      CI_ALPINE_TARGET: v3.21
       CI_ALPINE_REPO: 'https://ayakael.net/api/packages/forge/alpine'
-      CI_ALPINE_TARGET: v3.19
       FORGE_REPO_TOKEN: ${{ secrets.FORGE_REPO_TOKEN }}
       FORGE_REPO_USER: ${{ vars.FORGE_REPO_USER }}
     steps: