Require Jenkins 2.426.3 or newer (#296)

Also updates to Jenkins plugin parent pom 4.79 and to the latest release
of the plugin bill of materials that matches Jenkins 2.426.3.

pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>4.78</version>
+    <version>4.79</version>
     <relativePath />
   </parent>
 
@@ -51,7 +51,7 @@
   <properties>
     <changelist>-SNAPSHOT</changelist>
     <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
-    <jenkins.version>2.401.3</jenkins.version>
+    <jenkins.version>2.426.3</jenkins.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <revision>1.12.1</revision>
     <spotbugs.effort>Max</spotbugs.effort>
@@ -63,8 +63,8 @@
     <dependencies>
       <dependency>
         <groupId>io.jenkins.tools.bom</groupId>
-        <artifactId>bom-2.401.x</artifactId>
-        <version>2745.vc7b_fe4c876fa_</version>
+        <artifactId>bom-2.426.x</artifactId>
+        <version>2857.v01a_0144eb_20b_</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>