Pin MockBukkit to Maven Central 4.110.0 instead of jitpack snapshot

The floating jitpack snapshot v1.21-SNAPSHOT resolves to an ephemeral
git-described build whose jar/POM get evicted, breaking CI even on
unchanged commits. Switch to the equivalent stable Maven Central
coordinates (org.mockbukkit.mockbukkit:mockbukkit-v1.21:4.110.0).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: tastybento

pom.xml

@@ -51,7 +51,7 @@
         <!-- Testing dependencies -->
         <junit.version>5.10.2</junit.version>
         <mockito.version>5.11.0</mockito.version>
-        <mock-bukkit.version>v1.21-SNAPSHOT</mock-bukkit.version>
+        <mock-bukkit.version>4.110.0</mock-bukkit.version>
 
         <paper.version>1.21.11-R0.1-SNAPSHOT</paper.version>
         <bentobox.version>3.14.0</bentobox.version>
@@ -138,8 +138,8 @@
 
     <dependencies>
         <dependency>
-            <groupId>com.github.MockBukkit</groupId>
-            <artifactId>MockBukkit</artifactId>
+            <groupId>org.mockbukkit.mockbukkit</groupId>
+            <artifactId>mockbukkit-v1.21</artifactId>
             <version>${mock-bukkit.version}</version>
             <scope>test</scope>
         </dependency>