Update centres to 1.2.1

https://github.com/SiMolecule/centres/releases/tag/1.2.1

Note, 1.1 automatically pulled in guava, but 1.2.1 does not use it anymore,
hence an explicit dep is needed for guava.

cdkdepict-lib/pom.xml

@@ -43,12 +43,17 @@
     <dependency>
       <groupId>com.simolecule.centres</groupId>
       <artifactId>centres-cdk</artifactId>
-      <version>1.1</version>
+      <version>1.2.1</version>
     </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
       <version>1.7.36</version>
     </dependency>
+    <dependency>
+     <groupId>com.google.guava</groupId>
+     <artifactId>guava</artifactId>
+     <version>33.1.0-jre</version>
+    </dependency>
   </dependencies>
-</project>
+</project>