Closes #16: Release artifact for scala binary version 2.12

Updating dependencies:
* `scala.binary.version`: 2.11 -> 2.12
* `spark.version`: 2.4.0 -> 3.4.1

Also introducing `scala-2.11` profile and adding `commons-lang3` dependency explicitly as `commons-lang` became unresolvable after upgrading spark version.

pom.xml

@@ -39,8 +39,8 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-        <scala.binary.version>2.11</scala.binary.version>
-        <spark.version>2.4.0</spark.version>
+        <scala.binary.version>2.12</scala.binary.version>
+        <spark.version>3.4.1</spark.version>
     </properties>
 
     <dependencies>
@@ -67,6 +67,11 @@
             <version>${spark.version}</version>
             <scope>provided</scope>
         </dependency>
+       	<dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.5</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -242,6 +247,13 @@
                 <spark.version>1.5.2</spark.version>
             </properties>
         </profile>
+        <profile>
+            <id>scala-2.11</id>
+            <properties>
+                <scala.binary.version>2.11</scala.binary.version>
+                <spark.version>2.4.0</spark.version>
+            </properties>
+        </profile>
     </profiles>
 
 </project>

src/main/java/pl/edu/icm/sparkutils/avro/SparkAvroSaver.java

@@ -7,7 +7,7 @@
 import org.apache.avro.mapred.AvroKey;
 import org.apache.avro.mapreduce.AvroJob;
 import org.apache.avro.mapreduce.AvroKeyOutputFormat;
-import org.apache.commons.lang.StringUtils;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.hadoop.io.NullWritable;
 import org.apache.hadoop.mapreduce.Job;
 import org.apache.spark.api.java.JavaPairRDD;