Refactor to use try-with-resources for SnowflakeOutputConnection in C…

…opyTask

- Updated the `call` method in `CopyTask` to use try-with-resources for managing `SnowflakeOutputConnection`.
- Ensured proper resource management and automatic closure of the connection.
- Improved code readability and reliability by eliminating the need for explicit connection close in the finally block.

src/main/java/org/embulk/output/snowflake/SnowflakeCopyBatchInsert.java

@@ -427,8 +427,7 @@ public Void call() throws SQLException, InterruptedException, ExecutionException
       try {
         uploadFuture.get();
 
-        SnowflakeOutputConnection con = (SnowflakeOutputConnection) connector.connect(true);
-        try {
+        try (SnowflakeOutputConnection con = (SnowflakeOutputConnection) connector.connect(true)) {
           logger.info("Running COPY from file {}", snowflakeStageFileName);
 
           long startTime = System.currentTimeMillis();
@@ -446,9 +445,6 @@ public Void call() throws SQLException, InterruptedException, ExecutionException
           logger.info(
               String.format(
                   "Loaded file %s (%.2f seconds for COPY)", snowflakeStageFileName, seconds));
-
-        } finally {
-          con.close();
         }
       } finally {
         if (deleteStageFile) {