chore: add 2.12 scala version

Author: idirze

.build/.versions.yml

@@ -64,4 +64,4 @@ build-matrix:
   python_version: ['3.10', '3.11', '3.12']
   spark_version: [3.3.4, 3.4.4, 3.5.6, 4.0.1]
   java_version: [17]
-  scala_version: [2.13]
+  scala_version: [2.12, 2.13]