[SPARK-54844][BUILD] Upgrade maven.version to 3.9.12

### What changes were proposed in this pull request?

This PR upgrades the Maven version from 3.9.11 to 3.9.12 in the project's root POM file.

### Why are the changes needed?

Witness downloading issue in GHA

### Does this PR introduce _any_ user-facing change?

No. This is a build-only change that does not affect runtime behavior or user-facing features.

### How was this patch tested?

This change only updates the Maven version property in the POM file. The existing CI/CD pipelines will validate the build with the new Maven version.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #53610 from yaooqinn/mvn.

Authored-by: Kent Yao <[email protected]>
Signed-off-by: yangjie01 <[email protected]>

Author: yaooqinn

pom.xml

@@ -120,7 +120,7 @@
     <java.version>17</java.version>
     <java.minimum.version>17.0.11</java.minimum.version>
     <maven.compiler.release>${java.version}</maven.compiler.release>
-    <maven.version>3.9.11</maven.version>
+    <maven.version>3.9.12</maven.version>
     <exec-maven-plugin.version>3.6.1</exec-maven-plugin.version>
     <sbt.project.name>spark</sbt.project.name>
     <asm.version>9.9</asm.version>