Use HTTPS instead of HTTP to resolve dependencies

This fixes a security vulnerability in this project where the `pom.xml`
files were configuring Maven to resolve dependencies over HTTP instead of
HTTPS.

Signed-off-by: Jonathan Leitschuh <Jonathan.Leitschuh@gmail.com>

pom.xml

@@ -45,7 +45,7 @@
   <repositories>
     <repository>
         <id>repo.jenkins-ci.org</id>
-        <url>http://repo.jenkins-ci.org/public/</url>
+        <url>https://repo.jenkins-ci.org/public/</url>
     </repository>
     <repository>
         <id>lib</id>
@@ -97,7 +97,7 @@
   <pluginRepositories>
     <pluginRepository>
       <id>repo.jenkins-ci.org</id>
-      <url>http://repo.jenkins-ci.org/public/</url>
+      <url>https://repo.jenkins-ci.org/public/</url>
     </pluginRepository>
   </pluginRepositories>