Increase release tool java max heap size

Signed-off-by: Andrew Leonard <anleonar@redhat.com>

adopt-github-release/gradlew

@@ -44,7 +44,7 @@ APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx256m" "-Xms256m"'
+DEFAULT_JVM_OPTS='"-Xmx1g" "-Xms1g"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"