Use parent pom 4.77

https://github.com/jenkinsci/plugin-pom/releases/tag/plugin-4.77 describes
the changes in the 4.77 release of the parent pom.  Those changes include:

* jenkinsci/plugin-pom#880 - test harness update
* jenkinsci/plugin-pom#884 - spotbugs plugin update

Other dependencies were also updaetd in that parent pom.

Author: MarkEWaite

pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>4.76</version>
+    <version>4.77</version>
     <relativePath/>
   </parent>