Setup GitHub Actions for doing releases from the 0.3.x branch (#99)

Author: nrayburn-tech

.github/workflows/maven_release.yml

@@ -6,6 +6,7 @@ on:
   push:
     branches:
       - master
+      - 0.3.x
 
 jobs:
   build:

pom.xml

@@ -10,7 +10,7 @@
     <packaging>jar</packaging>
     <name>JsonNullable Jackson module</name>
     <description>JsonNullable wrapper class and Jackson module to support fields with meaningful null values.</description>
-    <version>0.2.9-SNAPSHOT</version>
+    <version>0.3.0-SNAPSHOT</version>
 
     <url>https://github.com/OpenAPITools/jackson-databind-nullable</url>
     <scm>