URL Cleanup (pgjdbc#92)

This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed Success
These URLs were switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.

* http://maven.apache.org/xsd/maven-4.0.0.xsd with 1 occurrences migrated to:
  https://maven.apache.org/xsd/maven-4.0.0.xsd ([https](https://maven.apache.org/xsd/maven-4.0.0.xsd) result 200).

# Ignored
These URLs were intentionally ignored.

* http://maven.apache.org/POM/4.0.0 with 2 occurrences
* http://www.w3.org/2001/XMLSchema-instance with 1 occurrences

Author: Spring Operator

pom.xml

@@ -18,7 +18,7 @@
         xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="
-                http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+                http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 
     <modelVersion>4.0.0</modelVersion>