fix: CI workflow — remove container, install V on runner

The vlang:alpine container lacks Node.js which Gitea Actions needs
for action steps (checkout@v4). Now installs V from source on the
default ubuntu-latest runner image instead.

.gitea/workflows/ci.yml

@@ -9,12 +9,16 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
-    container:
-      image: thevlang/vlang:alpine
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Install V
+        run: |
+          git clone --depth 1 https://github.com/vlang/v /opt/v
+          cd /opt/v && make
+          ln -s /opt/v/v /usr/local/bin/v
+
       - name: Build
         run: v -prod .