Add missing import.

Author: afoucret

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/CsvTests.java

@@ -128,6 +128,7 @@
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.in;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.notNullValue;
 
 /**