increment version to 4.1-beta1

 ref: https://lists.apache.org/thread/ho4r1lk2gsgs1z61ldzg64h84x3rbg4o
diff --git a/CHANGES.txt b/CHANGES.txt
index 17c4a10..1ecd879 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,4 @@
-4.1-alpha2
+4.1-beta1
  * We should not emit deprecation warning on startup for `key_cache_save_period`, `row_cache_save_period`, `counter_cache_save_period` (CASSANDRA-17904)
  * upsert with adder support is not consistent with numbers and strings in LWT (CASSANDRA-17857)
  * Fix race and return after failing connections (CASSANDRA-17618)
diff --git a/build.xml b/build.xml
index 1800c09..a0a0f19 100644
--- a/build.xml
+++ b/build.xml
@@ -33,7 +33,7 @@
     <property name="debuglevel" value="source,lines,vars"/>
 
     <!-- default version and SCM information -->
-    <property name="base.version" value="4.1-alpha2"/>
+    <property name="base.version" value="4.1-beta1"/>
     <property name="scm.connection" value="scm:https://gitbox.apache.org/repos/asf/cassandra.git"/>
     <property name="scm.developerConnection" value="scm:https://gitbox.apache.org/repos/asf/cassandra.git"/>
     <property name="scm.url" value="https://gitbox.apache.org/repos/asf?p=cassandra.git;a=tree"/>
diff --git a/debian/changelog b/debian/changelog
index 5c193b9..af8d520 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,4 +1,4 @@
-cassandra (4.1~alpha2) UNRELEASED; urgency=medium
+cassandra (4.1~beta1) UNRELEASED; urgency=medium
 
   * New release