Maven must run in batch mode when listing staged releases

Motivation:
We're grepping the output of the command, and terminal color codes get in the way of that.

Modification:
Ask maven to run in batch mode, to prevent colored output.

Result:
The list_staged_release.sh script no longer fails to find any staged releases in the maven output.

scripts/list_staged_release.sh

@@ -16,6 +16,6 @@
 # ----------------------------------------------------------------------------
 set -e
 
-RC_LIST=$(mvn org.sonatype.plugins:nexus-staging-maven-plugin:rc-list -DserverId=sonatype-nexus-staging -DnexusUrl=https://oss.sonatype.org | grep -A 2 "\[INFO\] ID                   State    Description")
+RC_LIST=$(mvn -B org.sonatype.plugins:nexus-staging-maven-plugin:rc-list -DserverId=sonatype-nexus-staging -DnexusUrl=https://oss.sonatype.org | grep -A 2 "\[INFO\] ID                   State    Description")
 STAGED=$(echo "$RC_LIST" | grep 'OPEN' | cut -f 2 -d ' ')
 echo "$STAGED"