Update maven repo to https

From Jan 15, 2020 Maven Central Repository no longer supports HTTP and requires that all requests to the repository are encrypted over HTTPS.
https://support.sonatype.com/hc/en-us/articles/360041287334

Change-Id: Iebcbaec6e8d19cf0f5d61b397305047386c68722
diff --git a/pom.xml b/pom.xml
index e7ff3eb..c0041c0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -65,7 +65,7 @@
         <repository>
             <id>central</id>
             <name>Central Repository</name>
-            <url>http://repo.maven.apache.org/maven2</url>
+            <url>https://repo.maven.apache.org/maven2</url>
             <layout>default</layout>
             <snapshots>
                 <enabled>false</enabled>