ci: stop release builds on pull requests

.github/workflows/java-publish.yml

@@ -13,11 +13,10 @@
 name: Build and publish Java packages
 on:
   push:
+    branches:
+      - main
     tags:
       - "v*"
-  pull_request:
-    paths:
-      - .github/workflows/java-publish.yml
 
 permissions:
   contents: read
@@ -48,8 +47,8 @@ jobs:
         run: |
           git config --global user.email "dev+gha@lancedb.com"
           git config --global user.name "LanceDB Github Runner"
-      - name: Dry run
-        if: github.event_name == 'pull_request'
+      - name: Build package
+        if: ${{ !startsWith(github.ref, 'refs/tags/v') }}
         run: |
           ./mvnw --batch-mode -DskipTests package -pl lancedb-core -am
       - name: Publish