chore(java-tests): bump docs java client pin to 6.3.0

6.3.0 is the current release; it keeps the java-v6 examples module compiling
(text2vec-digitalocean + tokenize APIs) and passes the server-side batching
test. Supersedes the 6.2.1 pin from the previous commit.

Author: g-despot

.github/workflows/docs_tests.yml

@@ -456,7 +456,7 @@ jobs:
 
       - name: Clone and build Java client SNAPSHOT
         run: |
-          JAVA_BRANCH="${{ inputs.java_client_branch || '6.2.1' }}"
+          JAVA_BRANCH="${{ inputs.java_client_branch || '6.3.0' }}"
           echo "📦 Building Java client SNAPSHOT from branch: $JAVA_BRANCH"
           git clone --depth 1 -b "$JAVA_BRANCH" https://github.com/weaviate/java-client.git /tmp/java-client
           cd /tmp/java-client

_includes/code/java-v6/pom.xml

@@ -30,7 +30,7 @@
     <dependency>
       <groupId>io.weaviate</groupId>
       <artifactId>client6</artifactId>
-      <version>6.2.1</version>
+      <version>6.3.0</version>
     </dependency>
 
     <!-- JUnit 5 for testing -->