fix: master/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMH2DATABASE-2331071
- https://snyk.io/vuln/SNYK-JAVA-COMH2DATABASE-2348247
- https://snyk.io/vuln/SNYK-JAVA-COMH2DATABASE-3009896
- https://snyk.io/vuln/SNYK-JAVA-COMH2DATABASE-31685

master/pom.xml

@@ -1,12 +1,12 @@
-<?xml version="1.0" encoding="UTF-8" ?>
+<?xml version="1.0" encoding="UTF-8"?>
 <project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 
   <!-- Include Sakai OSS parent, includes information for release management and project information common to all projects --> 
   <parent>
       <groupId>org.sakaiproject</groupId>
       <artifactId>oss-parent</artifactId>
       <version>1</version>
-      <relativePath></relativePath>
+      <relativePath/>
   </parent>
 
   <!-- Sakai Master defines all property versions and dependencyManagement used in Sakai -->
@@ -43,7 +43,7 @@
     <sakai.httpmime.version>4.5.13</sakai.httpmime.version>
     <sakai.httpclient5.version>5.1.3</sakai.httpclient5.version>
     <sakai.httpcore5.version>5.1.3</sakai.httpcore5.version>
-    <sakai.ignite.version>2.12.0</sakai.ignite.version>
+    <sakai.ignite.version>2.15.0</sakai.ignite.version>
     <sakai.ignite.spring.ext.version>1.0.0</sakai.ignite.spring.ext.version>
     <sakai.gridgain.version>8.8.7</sakai.gridgain.version>
     <sakai.jackson.version>2.13.2</sakai.jackson.version>
@@ -103,7 +103,7 @@
     <sakai.build.directory>target</sakai.build.directory>
     <maven.test.redirectTestOutputToFile>false</maven.test.redirectTestOutputToFile>
     <!-- Default empty unless profile activation -->
-    <random-source></random-source>
+    <random-source/>
 
     <!-- These should only be updated when the webjars version is updated -->
     <ckeditor.autosave.version>0.18.6</ckeditor.autosave.version>