Fix some of the warnings emitted by maven during build (#1363)

* Set the source encoding in the pom.

This stops the following warning from being emitted in our logs:

```
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
```

* Replace deprecated systemProperties.

The recommended replacement is systemPropertyVariables, documented [here](https://maven.apache.org/surefire/maven-surefire-plugin/examples/system-properties.html).

amazon-kinesis-client/pom.xml

@@ -228,16 +228,10 @@
           <excludes>
             <exclude>**/*IntegrationTest.java</exclude>
           </excludes>
-          <systemProperties>
-            <property>
-              <name>sqlite4java.library.path</name>
-              <value>${sqlite4java.libpath}</value>
-            </property>
-            <property>
-              <name>awsProfile</name>
-              <value>${awsProfile}</value>
-            </property>
-          </systemProperties>
+          <systemPropertyVariables>
+            <sqlite4java.library.path>${sqlite4java.libpath}</sqlite4java.library.path>
+            <awsProfile>${awsProfile}</awsProfile>
+          </systemPropertyVariables>
         </configuration>
       </plugin>
       <plugin>

pom.xml

@@ -34,6 +34,7 @@
 
   <properties>
     <awssdk.version>2.25.64</awssdk.version>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
 
   <licenses>