Update solanaj dependency to version 1.18.2

Upgraded the solanaj library from version 1.18.1 to 1.18.2 in the README.md dependency snippet. This ensures compatibility with the latest features and bug fixes provided in the new version.

docs/README.md

@@ -50,7 +50,7 @@ Add the following Maven dependency to your project's `pom.xml`:
 <dependency>
     <groupId>com.mmorrell</groupId>
     <artifactId>solanaj</artifactId>
-    <version>1.18.1</version>
+    <version>1.18.2</version>
 </dependency>
 ```